Sneak Peek: "So...That's a No?"

The impact of a single endorsement in a political campaign is debatable.

Does the opinion of one person, whether it's a big name political leader like Jimmy Carter or Al Gore or a bleached blond D-List reality TV star like Heidi Montag, actually matter to voters? Will an endorsement help a voter make up their mind? Change their mind? Get them to the polling station?

Basically, endorsements matter unless they don't. But the free media that an endorsement provides may be more valuable and have more legs than the announcement itself.

Take Bill Richardson's bombshell that he was backing Barack Obama. This was seen as a coup for Obama because of Richardson's ties to the Clintons and marked the second former Democratic rival to get in his corner (after Chris Dodd). Though it came over two weeks too late to be helpful in Texas, Richardson's support could be key to bringing Hispanic voters onto the Obama campaign.

Richardson's endorsement was two weeks ago – an eternity in politics. Yet his name (and support for Obama) is still in the headlines and the endorsement continues to reverberate through the campaign because Team Clinton, clearly still smarting, keeps putting it back in the news. From James Carville's Judas comments, to Bill Clinton's reported red-faced rant, to Hillary Clinton declaration that Obama "cannot win" the general election, the media gets to regurgitate the "Richardson is on Team Obama" storyline.

Today Hillary Clinton denied that she told Richardson that Obama "cannot win" a general election against John McCain.

"That's a no," Clinton told reporters at the end of a press conference in Burbank, CA, when asked if made the comment to Richardson, per ABC News' Eloise Harper.

"We have been going back and forth in this campaign of who said what to whom and let me say this, that I don't talk about private conversations but I have consistently made the case that I can win," she said.

ABC News' George Stephanopoulos reported on Wednesday's World News that sources with direct knowledge of the conversation between Sen. Clinton and Richardson, prior to the Governor's endorsement of Obama say she told him flatly, "He cannot win, Bill. He cannot win."

Martin Luther King Jr. Anniversary

Friday is the 40th anniversary of the assassination of Dr. Martin Luther King Jr. and both Hillary Clinton and John McCain will detour from the campaign trail to make appearances in Memphis.

Clinton posted a video tribute to Dr. King on her campaign's web site, recalling how she heard him speak in Chicago when she was a young girl. "He called his sermon that evening 'Remaining Awake Through a Great Revolution.' Dr. King challenged all of us there, as he did throughout his life, to stay awake during the great civil rights revolution that was sweeping our country."

McCain will deliver remarks to the Southern Christian Leadership Conference and lay a remembrance wreath National Civil Rights Museum at the former Lorraine Motel where King was assassinated.

ABC News' Jake Tapper writes about McCain's "complicated history" with Martin Luther King Jr. Day – as a young congressman in 1983, McCain voted against legislation designating a federal holiday for the civil rights activist.

"In December 1999 McCain told NBC's Tim Russert, "on the Martin Luther King issue, we all learn, OK? We all learn. I will admit to learning, and I hope that the people that I represent appreciate that, too. I voted in 1983 against the recognition of Martin Luther King….I regret that vote,'" Tapper writes.

Barack Obama will not be in Memphis but will make remarks at a town hall in Fort Wayne, IN to note the significance of the day.

Per ABC News' Sunlen Miller, Obama will talk about the struggle for economic justice that Dr. King was fighting for in Memphis forty years ago and how that's a struggle that continues today. Obama will call on Americans to complete the work that King began and help struggling families today by coming together as Americans.

Add this to the list of "Things We Never Thought We Would Write" in this campaign season – the center of the Democratic political universe tomorrow? Grand Forks, ND.

Both Obama and Clinton address the North Dakota Democratic-NPL State Convention which competes with next week's NCAA men's ice hockey Frozen Four as the most exciting and buzzed-about event for Sioux State residents this month.

The Labor Department releases unemployment figures for March on Friday morning. The numbers come out at 8:30 am ET, so expect those campaign statements to hit inboxes shortly thereafter.

The FEC reports are not due until April 20th, but the Obama campaign announced that it raised over $40 million from 442,000 contributors and the Clinton campaign said it raised at least $20 million for the month of March.

ABC News' Kate Snow reports that on a conference call with reporters earlier today, Clinton campaign Communications Director Howard Wolfson downplayed the fundraising gap.

"We knew he was going to outraise us. He has for the last several months," Wolfson said.

Wolfson insisted -- as the campaign has repeatedly said-- that Clinton has enough money to be competitive and successful moving forward.

On the campaign trail. . .


-- 11:00 am ET: Attends town hall meeting with voters, Fort Wayne, IN

-- 6:30 pm ET: Addresses the North Dakota Democratic-NPL State Convention, Grand Forks, ND


-- Attends event for the 40th anniversary of the assassination of Dr. Martin Luther King, Jr., Memphis, TN

-- 8:30 pm ET: Addresses the North Dakota Democratic-NPL State Convention, Grand Forks, ND


-- 8:30 am ET: Attends event with voters, Pembroke, NC

-- 10:15 am ET: Attends event with voters, Laurinburg, NC

-- 1:00 pm ET: Attends event with voters, Monroe, NC

-- 3:00 pm ET: Attends event with voters, Charlotte, NC

As for the Republicans. . .


-- 12:00 pm ET: Delivers remarks to the Southern Christian Leadership Conference, Memphis, TN

-- 2:00 pm ET: Holds media availability, Memphis, TN

-- 2:45 pm ET: Places a remembrance wreath, Memphis, TN

At the White House and Beyond. . .


-- 1:50 am ET: Attends a summit meeting of the NATO Ukraine Commission, Bucharest, Romania

-- 4:00 am ET: Attends summit meeting of the NATO Russia Council, Bucharest, Romania

-- 6:15 am ET: Meets with the Prime Minister of Romania, Bucharest, Romania

-- 12:25 pm ET: Participates in arrival ceremony, Zagreb, Croatia

-- 12:40 pm ET: Meets with the President of Croatia, Zagreb, Croatia

-- 1:50 pm ET: Attends social dinner with the President of Croatia, Zagreb, Croatia


-- 8:30 am ET: Releases the unemployment report for March, Washington, DC


ABC News' Brian Ross and Avni Patel Reports: The Clinton Tax Returns: What Will They Reveal? LINK

ABC News' Sunlen Miller Reports: Cha-Ching! Obama Takes in $40 Million in March LINK

ABC News' Z. Byron Wolf Reports: Compromise Foreclosure Bill Sees Fissures in Senate LINK

ABC News' Eloise Harper Reports: Clinton Denies Saying Obama 'Cannot Win' LINK

ABC News' Jake Tapper Reports: Gov. Rendell: There 50% About Barack Obama We Don't Know Yet LINK

ABC News' Jan Simmonds Reports: McCain Lays Out His Principles, Shaped by His Past LINK

ABC News' Eloise Harper Reports: Clinton: 'I Feel Like Paulette Revere' LINK

ABC News' Jake Tapper Reports: The Complicated History of John McCain and MLK Day LINK

ABC News' Melissa Chee Reports: The Price of Protection LINK

ABC News' Jake Tapper Reports: Obama Is Smokin' LINK

ABC News' Z. Byron Wolf Reports: Senate Honors War Dead: 264 Pages, 4009 Names LINK

ABC News' Jake Tapper Reports: Could Bob Barr Hurt McCain? Obama? Clinton? LINK

ABC News' Kate Snow and Sunlen Miller Report: Clinton Fundraising for March LINK

ABC News' Jake Tapper Reports: Who's Offering a 3rd Bush Term on Energy? LINK

ABC News' Z. Byron Wolf Reports: In Defense of Congressional Vacations LINK

ABC News' Raelyn Johnson Reports: Edwards Would Not Accept Possible VP Nod LINK


Dueling 3 a.m. Ads
Clinton and McCain air dueling commercials about the economy. LINK

The Pitfalls of Polling
The difficulty pollsters have had this year in pinning down the public mood. LINK

Candidate Flops
Trying to look like the 'common man' on the trail can have its pitfalls. LINK

Clinton 3am Ad Hammers McCain
Clinton Camp releases new ad in Pennsylvania blasting McCain on the economy. LINK

McCain Fires Back With His Own 3am Ad
McCain responds to Clinton's latest ad criticizing McCain on the economy. LINK

Bush's NATO Agenda
President Bush's agenda gets a mixed response at NATO summit. LINK

The Bottom Line on Obama vs. Clinton
George Stephanopoulos weighs in on the latest campaign battles. LINK

Tax Time for the Clintons
The tax returns will answer questions on how they made their millions. LINK

Governor Rendell: Obama 'Hasn't Been Vetted'
The PA governor on Clinton's chances, racial politics in PA, and the McGreevey/Spitzer scandals. LINK

Hillary to Richardson: 'Obama Can't Win'
George Stephanopoulos reports Clinton Camp is pressing super delegates. LINK

'Pig Book' Sums Up Pork Spending
Watchdog group figures out how much congressional pet projects cost you. LINK