THE NOTE: Final Four:

Jan. 31, 2008 -- We'll be short one son of a mill worker in Los Angeles Thursday night. On Wednesday, the Republican candidates somehow went 90 entire minutes debating each other without anyone saying some variation of, "as I demonstrated on 9/11."

So we have our Final Four, the early-voting states finally clearing the field the way they were designed to do (and maybe helped by self-fulfilling mainstream media prophecies; lots of brackets filled out last March had these pairs as the last candidates standing). The matchups are set for Feb. 5 -- and while it's easier to make the delegate math work now, we're still a long way from knowing who our nominees are.

Thursday at 8 pm ET, we get the Big Dance, the showdown we've been waiting patiently for: Two Democratic candidates on a debate stage, both vying to make history, but only one, of course, destined to come out on top.

Sen. Hillary Rodham Clinton and Sen. Barack Obama come to this fight with their differing backgrounds and messages -- but their biggest challenge this week is a tactical one: managing a primary schedule that's designed to keep things interesting for a long while. On Thursday, they'll again seek to find differences where there often aren't any, with the race already having taken a turn to the personal.

"Clinton and Obama are in a frequently nasty personal fight, but not one that reflects deep ideological divisions or, as yet, threatens to leave the party badly divided once it is over," Dan Balz and Anne Kornblut write in The Washington Post. "Republicans on the other hand, see the prospect of a clear fracture in their coalition as a result of the nomination contest."

On stage on Thursday, there will be "no foils, no subtle alliances and no triangulation," the Chicago Tribune's Christi Parsons and Mike Dorning write.

So we can expect to hear about our friends Rezko and Wal-Mart (more on that below) -- and just perhaps about "two Americas," even without John Edwards on stage. With Edwards ending his fight, both candidates are making quick plays for his former supporters -- and maybe for Edwards himself.

"Mr. Edwards was not saying what he would do, but aides to Mr. Obama and Mrs. Clinton said they planned to push themes in the days ahead that were directed at supporters of Mr. Edwards, who are now in the market for a new candidate," Adam Nagourney and Jeff Zeleny write in The New York Times.

One of the many things that makes these races fun is that both parties' establishments are deeply split. Clinton, D-N.Y., and Obama, D-Ill., each have their own claims to different Democratic establishments; now, with all the principals on the trail, we'll see if the Kerry-Kennedy combo can match Bill Clinton in star power/news value/real impact.

Clinton and Obama enter this critical phase with different messages -- one more taste of the role reversals that have marked this chaotic political year. Obama traveled to Denver -- where he hopes to cap his journey to the nomination this summer -- to lay out the stakes as he sees them (and in his most explicitly Clinton-bashing way yet).

Read between these lines: "We can be a party that tries to beat the other side by practicing the same do-anything, say-anything, divisive politics that has stood in the way of progress, or we can be a party that puts an end to it," Obama said, per ABC's David Wright, Andy Fies, and Sunlen Miller.

"I know it is tempting -- after another presidency by a man named George Bush -- to simply turn back the clock, and to build a bridge back to the 20th century."

It was a quick pivot to the one-on-one that the campaign now is: "His barbs never mentioned his rival by name, but Obama took a direct slap at Clinton's past divisiveness and her failure to achieve healthcare reform as first lady or senator," Maria L. La Ganga and Peter Nicholas write in the Los Angeles Times.

Responded Clinton, in an AP interview: "That certainly sounds audacious, but not hopeful."

Clinton is talking substance (and even "hope" of her own), planning a "national town hall" and releasing a new ad that focuses on the economy and the housing crisis.

And -- just as importantly -- she's trying to reclaim her campaign: Asked whether she can control her husband, she responded: "Oh, of course. You know, there's only one president at a time," Clinton told ABC's Cynthia McFadden for a "Nightline" piece that aired Wednesday.

On her husband's recent comments: "I think if whatever he said -- which was certainly never intended to cause any kind of offense to anyone -- that is the furthest thing from him," Clinton told McFadden. "And yet if it did take offense, I take responsibility and I'm sorry about that because we have nothing but the best intentions and the most hope about what we can do for our country."

This is another way to put it: "This is my campaign, it is about my candidacy," Clinton said on Wednesday, per ABC's Kate Snow, Jennifer Parker, Sarah Amos, and Eloise Harper.

(And on the "snub" -- she's got the line down pat: "I reached out my hand in friendship and unity and I'm still reaching it out and I expect we'll shake hands at the debate in California. Was it intentional, McFadden wanted to know? "You'll have to ask him. I don't know. But the differences between us are nothing compared to the differences between us and the Republicans. That's what I want people to stay focused on.")

On the Republican side, the endorsements that Sen. John McCain is picking up -- former mayor Rudolph Giuliani, R-N.Y., on Wednesday, with Gov. Arnold Schwarzenegger, R-Calif., coming Thursday, at 12:30 pm ET -- are big-time names, though they hardly hail from the conservative pantheon. (They were featured at the 2004 convention precisely because they looked and sounded different than so many of the delegates they addressed.)

They are trying to end former governor Mitt Romney's challenge -- but even as the establishment stirs, the stop-McCain forces remain potent (if less energized), in a race with clear ideological splits.

"Democrats have two candidates of unusual talent and political dexterity. Their political bases are equally formidable, as is their ability to raise money," Adam Nagourney writes in the Times.

"Republicans have two candidates who are scrappy and nimble campaigners. Both have also had the onus of reading their own premature political obituaries this year. But they have yet to inspire the enthusiasm among Republicans that Mrs. Clinton and Mr. Obama have inspired among Democrats."

The Republicans' final debate before Super Tuesday wasn't a clean one-on-one -- Mike Huckabee and Ron Paul joined the two men who might actually win the nomination. And neither was it a soaring discussion of vital issues; McCain and Romney mainly looked tired -- of each other, of these debates, and just in general.

The personal animosity was palpable. "John McCain's solidified frontrunner status didn't cause him to let up on taking the fight to Mitt Romney during the debate tonight at the Reagan Presidential Library," ABC's David Chalian writes.

"The genuine dislike that has apparently developed over the last year between the remaining two serious contenders for the Republican presidential nomination was on display during their final debate before Super Tuesday, when Republicans will go to the polls in 21 states."

Romney played more defense than offense, and did nothing that seems likely to stop McCain's roll through California -- which will continue with the Schwarzenegger endorsement on Thursday. "The endorsement allows McCain to soak up another day of free media attention while both Romney and McCain determine if, where, and when to advertise on television before Super Tuesday," Chalian reports.

At the debate, McCain seemed to come out against his own immigration bill (straight talk alert!), and Romney may have scored some point in accusing him of "dirty tricks" that distort his record. But the very fact that they were bickering about Iraq -- while engaging in an agreeable discussion on the economy -- shows why the evening was a disappointment to Romney.

"In a repeat of what happened in a Florida debate last weekend, Romney was drawn into a heated back-and-forth over his views on the war, diverting attention from his focus on the economy and on McCain's many examples of political apostasy," Politico's Jonathan Martin writes.

"McCain, leaning back in his chair and sporting a sly grin, offered little evidence to bolster his original charge, content to let Romney explain himself."

Unlike the Democratic race, the Republican contest could really be over by Feb. 5, with all those winner-take-all states voting. We find out Thursday how much more of his own fortune Romney dumped into his campaign by the end of December, with the filing deadline for fourth-quarter FEC reports.

But as he readies himself for the final brawl, could Romney be checking his wallet at the door? "Romney signaled Wednesday he's not ready to finance a costly campaign in the states holding primaries and caucuses next week," the AP's David Espo reports.

"Romney's campaign was not attempting to purchase television advertising time in any of the 21 states on the calendar for Feb. 5. Instead, the former Massachusetts governor's current plans call for campaigning in California and other primary states, said the officials, who had knowledge of the internal discussions. There would be organizational efforts primarily for caucus states."

This could change -- but if it doesn't, we can take the next week off: If Romney doesn't place a big buy in Feb. 5 states, John McCain will be the Republican nominee. "Washington may be broken -- as Mitt Romney likes to say -- but the question now hanging over his campaign is whether he is willing to break the bank to go to Washington and fix it," Michael Levenson writes in The Boston Globe.

Wednesday was a day of dramatic exits, and Edwards, D-N.C., left as he started: in New Orleans, talking about his cause of eradicating poverty. "It's time for me to step aside so that history can blaze its path," Edwards said, per ABC's Raelyn Johnson, Ed O'Keefe, and Jennifer Parker. On his conversations with his now-former rivals: "They have both pledged to me, and more importantly through me to America, that they will make ending poverty central to their campaign for the presidency," Edwards said.

"Edwards leaves the race having made a big impact on the two remaining candidates. His populist rhetoric forced his rivals to compete for union support, and he was the first out of the gate with detailed plans for universal healthcare and education, putting pressure on the field to match him," Time's Jay Newton-Small reports.

Who it helps depends on the state, adding just one more element to the complicated calculus of delegate math that's vexing the campaigns these days. It seems inconceivable that he'd wind up supporting Clinton -- whom he depicted as the "status quo" in a cause that was built on the need for a revolution -- but an endorsement may not change any equation anyway.

Endorsements do seem to be boosting McCain, who rode late embraces by Gov. Charlie Crist, R-Fla., and Sen. Mel Martinez, R-Fla., to victory in Florida, and now is adding to his Feb. 5 pile. As expected, Giuliani made his flight to California to make his backing formal, in a classy appearance where he heaped praise on his onetime rival but longtime friend: "He's an American hero," Giuliani said, per ABC's Jake Tapper.

Schwarzenegger's backing will make McCain begin to look unstoppable in California, the biggest delegate prize (though the GOP awards delegates by congressional district). The Los Angeles Times' Mark Z. Barabak and Evan Halper call it "a marriage of political mavericks," and -- Schwarzenegger's decision to abandon his neutrality pledge notwithstanding -- it helps McCain "fasten his grip on the GOP nomination."

One of the (many) dynamics that favor McCain: "Without Mr. Giuliani in the race, Mr. McCain now has a clear path to win the moderate Republicans and independents they had been sparring over," the Washington Times' Stephen Dinan writes.

"His chief rival, former Massachusetts Gov. Mitt Romney, still has to battle former Arkansas Gov. Mike Huckabee for conservative voters in the slate of primaries to be held next week."

The anti-McCain forces almost seem resigned to his march toward the nomination. "Some conservatives are making a last-ditch attempt to block Senator McCain's path to the Republican presidential nomination, but there are indications that they may have trouble building a broad and well-funded anti-McCain coalition," Josh Gerstein writes in the New York Sun.

"Rush Limbaugh . . . sounded resigned yesterday to the prospect that the Arizona senator will be the Republican nominee." Said Rush: 'It looks like McCain's pretty far down the line now to having wrapped this up."

Just don't call McCain the frontrunner: "The campaign is back where it started: with McCain as the man with the momentum, squaring off against Romney, a challenger who is willing to spend whatever it takes to win," Newsweek's Holly Bailey writes.

For a moment, let's savor the simplicity: "With just five days until more than 20 states vote on Feb. 5, the thinning of the fields makes the two races less chaotic and offers simpler choices for voters across the country, creating what could be an unprecedented national referendum on presidential nominees," Peter Canellos writes in The Boston Globe.

Lots of California dreaming on the trail today. Get all the candidates' schedules in The Note's "Sneak Peek."

Also in the news:

ABC's Brian Ross obtained tapes of Wal-Mart stockholder meetings from Sen. Clinton's time on the company's board of directors. "In six years as a member of the Wal-Mart board of directors, between 1986 and 1992, Hillary Clinton remained silent as the world's largest retailer waged a major campaign against labor unions seeking to represent store workers," Ross, Maddy Sauer, and Rhonda Schwartz write.

"An ABC News analysis of the videotapes of at least four stockholder meetings where Clinton appeared shows she never once rose to defend the role of American labor unions," they write. This is Clinton, from June 1990, a period during which Wal-Mart was actively working to stymie unionization efforts: "I'm always proud of Wal-Mart and what we do and the way we do it better than anybody else."

But Camp Clinton's depiction of Clinton as a strong advocate for women and the environment gets a boost from the mouth of Wal-Mart founder Sam Walton, in 1987: "We've got a very strong-willed young woman on our board now; her name is Hillary."

Even when Bill is behaving, he shows up in the news. The New York Times examines the role he played in helping one of his foundation's big benefactors, Frank Giustra, in securing a mining deal in Kazakhstan. Kazakhstan's president "walked away from the table with a propaganda coup, after Mr. Clinton expressed enthusiastic support for the Kazakh leader's bid to head an international organization that monitors elections and supports democracy," the Times' Jo Becker and Don Van Natta Jr. write.

"Mr. Clinton's public declaration undercut both American foreign policy and sharp criticism of Kazakhstan's poor human rights record by, among others, Mr. Clinton's wife, Senator Hillary Rodham Clinton of New York," they write.

"Within two days, corporate records show that Mr. Giustra also came up a winner when his company signed preliminary agreements giving it the right to buy into three uranium projects controlled by Kazakhstan's state-owned uranium agency, Kazatomprom."

The Chicago Tribune's Bob Secter and David Jackson sort through why Obama has had to repeatedly shed new rounds of Rezko-tainted donations: They're not easy to find.

"The numbers depend on assumptions made about why a donor gave in the first place," they write. "It remains unclear whether Obama's campaign has dragged out the process of shedding Rezko money because it was having a difficult time determining the nature of those donations, or if the campaign was reluctant to look hard for them."

The New York Post goes with Obama -- but really, the ed board is going against Clinton: "Does America really want to go through all that once again? It will -- if Sen. Clinton becomes president."

Karl Rove proposes some "new rules" of elections in a Wall Street Journal op-ed (and don't you think Bill Maher is made proud?).

You didn't think Congress could consider a bill without getting detoured through an immigration debate, did you? This time, it's the economic stimulus package: "This bill allows people who are here illegally in this country to get the rebates," said Sen. John Ensign, R-Nev., per the Las Vegas Sun. "That's something I have concern with." So did the Senate Finance Committee -- the apparent loophole was quickly closed.

Michelle Malkin wants to see the issue brought up on the campaign trail.

Rep. Tom Davis, R-Va., makes it 28 House Republicans headed for the exits -- and 24 (and counting) open GOP seats on Election Day 2008, compared with five for the Democrats. "A swelling exodus of senior Republican incumbents from the House, worsened by a persistent disadvantage in campaign money, threatens to cripple Republican efforts to topple the Democratic majority in November," Carl Hulse and David Herszenhorn report in The New York Times.

With Edwards and Dennis Kucinich out . . . here comes Ralph Nader. Nader has formed a presidential exploratory committee, and told ABCNews.com that he'll run for president if he's convinced over the next month that he can raise $10 million over the course of his campaign, and that he can attract the pro bono legal help he'll need to get on state ballots. His assessment of Obama: "His record in the Senate is pretty mediocre," Nader said. "His most distinctive characteristic is the extent to which he censors himself. He hasn't performed as a really progressive first-term senator would."

Here's an intriguing endorsement possibility: "MoveOn.org, the powerhouse grassroots organization that showered Democrats with more donations in the midterms than almost any other liberal PAC, is asking its members whether to host a virtual vote on Thursday to endorse Barack Obama or Hillary Clinton for President," The Nation's Ari Melber reports.

Todd Domke uses his Boston Globe column to develop Mayor Michael Bloomberg's dream scenario: Hillary vs. Mitt. "Mitt panders to 30 percent on the right, Hillary panders to 30 percent on the left, I'll pander to the 80 percent who are tired of being pandered to," he imagines Bloomberg, I-N.Y., saying.

The kicker:

"I don't think that soon-to-be-Secretary Rumsfeld is in any way out of the mainstream of American political life. And I would argue that the same would be true for the vast majority of the Bush nominees, and I give him credit for that." -- Barack Obama, the a state senator, in a January 2001 TV interview.

"I love anything peach." -- Hillary Clinton, serving cobbler to the traveling press (and just maybe giving a shout-out to fellow peach-lover Bill Burton, of the Obama campaign).

"I can't answer. I'm sitting shiva right now." -- Rudy Giuliani "confidante," to the New York Post.

"The New York lifestyle hasn't gone over [in] some places. It seemed like the more people got acquainted with him, the less they liked him." -- Sen. Chuck Grassley, R-Iowa, on why the Big Apple schtick didn't play in the heartland, to the New York Daily News.

I'll be live-blogging during Thursday night's Democratic debate, the first one-on-one of the cycle, starting at 8 pm ET. Be part of the conversation at ABCNews.com's Political Radar.

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