By MICHAEL FALCONE ( @michaelpfalcone )

NOTABLES

• BREWER DECIDES: "Gov. Jan Brewer on Wednesday vetoed a Republican bill that set off a national debate over gay rights, religion and discrimination and subjected Arizona to blistering criticism from major corporations and political leaders from both parties," the Associated Press' Bob Christie reports from Phoenix. "Loud cheers erupted outside the Capitol building immediately after Brewer made her announcement. 'My agenda is to sign into law legislation that advances Arizona," Brewer said at a news conference. 'I call them like I see them despite the cheers or the boos from the crowd. After weighing all the arguments, I have vetoed Senate Bill 1062 moments ago.' The Republican governor said she gave the legislation careful deliberation in talking to her lawyers, citizens, businesses and lawmakers on both sides of the debate. Her office said it received more than 40,000 calls and emails on the legislation, with most of them urging a veto." http://abcn.ws/1hkDF9j

• REACTIONS POUR IN: Celebrities and politicians took to social media sites responding to Gov. Brewer's veto. Here's a sampling: http://abcn.ws/1ft0Mzj

• WHAT'S NEXT?: According to the AP: "Similar religious-protection legislation has been introduced in Ohio, Mississippi, Idaho, South Dakota, Tennessee and Oklahoma, but Arizona's plan is the only one that has been passed by a state Legislature. The legislation was withdrawn in Ohio on Wednesday, and similar bills are stalled in Idaho and Kansas. The push in Arizona comes as an increasing number of conservative states grapple with ways to counter the growing legality of gay marriage. Arizona has a ban on gay marriage. Federal judges have recently struck down those bans in Utah, Oklahoma and Virginia, but those decisions are under appeal." http://abcn.ws/1hkDF9j

ANALYSIS

ABC's RICK KLEIN: By the time Gov. Jan Brewer made her decision, there was little deciding left to be done. That makes Brewer's veto something more than a rejection of a single law - and something of a social and cultural moment. Part of what makes the last week remarkable is that after the issue of the Arizona bill went national, we saw a national conversation that felt distinctly one-sided. A bill that was pursued as part of a national pushback against expanded gay rights (including gay marriage) suddenly had few prominent friends in the conservative movement. And a solidly conservative governor - perhaps best known previously for her immigration stands, and a particular finger-wag aimed at President Obama - was persuaded by national business leaders, social groups, and prominent Republican officials. If Brewer didn't really have a choice, it's because her state and a nation had spoken. Consider it another marking point in a changing nation.

ABC's JEFF ZELENY: The fight for control of the Senate became a bit rockier for Democrats yesterday. Colorado is emerging as a key battleground in the midterm election campaign, with a fast-moving series of events yesterday changing the landscape of the Senate map. Sen. Mark Udall, a Colorado Democrat seeking a second term, was once thought to be on a glide-path to re-election. But stiff headwinds for Democrats have suddenly turned his seat into a hot commodity. Rep. Cory Gardner, a Colorado Republican had been aggressively recruited by party leaders to run for the Senate. He had rebuffed the recruiting efforts - until now. Three Republican officials familiar with his decision tell ABC News that he is poised to jump into the race later this week. And shortly after The Denver Post first reported news of his decision yesterday, one of his leading Tea Party challengers, Ken Buck, decided to abandon his Senate bid to run for Gardner's House seat. "It's a game-changing day," Dick Wadhams, a former chairman of the Colorado Republican Party, told ABC News. "The brutal truth was we didn't have a very strong candidate running. We had a retread who was the front-runner. Now, we have a candidate who Republicans across the board can rally around." To win control of the Senate, Republicans must pick up six seats. Gardner's decision to run makes Colorado instantly more competitive and offers Republicans another path. http://abcn.ws/NyfskL

BUZZ

OBAMA TO INTRODUCE INITIATIVE TO LIFT UP MINORITY MEN. President Obama today will try to tackle a cause that is deeply personal for him: helping minority boys succeed, ABC's MARY BRUCE notes. This afternoon, the president announces his new "My Brother's Keeper" initiative, a public-private effort "to make sure that every young man of color who is willing to work hard and lift himself up has an opportunity to get ahead and reach his full potential." The president will also meet with foundation and business leaders in the State Dining Room to discuss the initiative. At today's event, will be an inspiring group of young men from Chicago who have had a profound impact on the president. One year ago, Obama sat in a Hyde Park classroom and shared his personal story with a group of African-American, male students struggling to overcome their circumstances and navigate the dangers of the South Side. The president was so impressed with the young men and touched by their raw conversation, that he invited them to celebrate Father's Day at the White House in June - a day many of them had never marked. Members of the group, "Becoming A Man," will be back at the White House as the president makes his announcement. They will be joined by members of similar mentoring groups from across the country and other stakeholders.

SETH ROGEN SPEAKS OF FAMILY EXPERIENCE WITH ALZHEIMER'S. Actor Seth Rogen is best known for his role as a pot-smoking jokester in comedic hits like "Knocked Up" and "Pineapple Express," but he joined the ranks yesterday of other celebrities who have brought their Hollywood star power to Capitol Hill, ABC's ARLETTE SAENZ reports. "Thank you for the opportunity to testify today, and for the opportunity for me to be called an 'expert' at something, because it makes me feel smart," Rogen, a celebrity champion for the Alzheimer's Association, said before a Senate Appropriations subcommittee. "I should first answer a question I assume many of you are asking: Yes, I'm aware this has nothing to do with the legalization of marijuana. In fact, if you can believe it, this concerns something that I find even more important." The 31-year-old actor's personal experience with the disease (his mother-in-law suffers from it) was what brought him before the Senate panel. Rogen, along with wife Lauren Miller, founded Hilarity for Charity, an advocacy group that raises money and awareness for Alzheimer's disease. Rogen and Miller became active in the Alzheimer's community after Miller's mother was diagnosed with the disease at the age of 55. Miller's grandparents also died of the disease.

BOEHNER ON TAX REFORM: 'BLAH BLAH BLAH,' 'AH, JESUS'. House Ways and Means Chairman Dave Camp, R-Mich., is unveiled a tax-reform proposal yesterday that's expected to include broad simplifications to the tax code, along with lower rates for higher incomes and surtaxes on certain types of income for the wealthy, ABC's CHRIS GOOD reports. At the weekly GOP leadership news conference, House Speaker John Boehner stopped short of endorsing the plan as the Republican Party's stance on taxes. "You're getting a little bit ahead of yourself," Boehner said when asked if Camp's plan is the GOP plan. "We've talked about this and Chairman Camp's worked on this for years. It's time to have a public conversation about the issue of tax reform. And so I welcome the conversation." Asked about specifics, Boehner was in no mood to delve into the sticky politics of a topic filled with special-interest land mines for politicians to step on. "Blah blah blah," Boehner replied, smiling. "The idea of tax reform is to get our economy going again, provide better - more economic growth, more jobs and higher wages. The way you do that is you bring down rates. And to bring down rates, you clean out a lot of the garbage that's in there and the special-interest issues that are in there," Boehner said. "This is the beginning of that conversation." Asked about the likelihood of a vote this year on Camp's bill and the potential for support from Senate Republican leaders, Boehner replied, laughing, "Ah, Jesus." http://abcn.ws/1o68b7h

IN CASE YOU MISSED IT

BEN AFFLECK AND JOHN KERRY'S SUPER-AWKWARD MOMENT. Sometimes even an Oscar-winning actor and the nation's top diplomat have clumsy moments, notes ABC's ALI WEINBERG. Before they got down to the serious business of talking about the humanitarian crisis in the Congo yesterday, actor Ben Affleck and Secretary of State John Kerry had to take part in the time-honored ritual of gripping-and-grinning before the press. But the "grip" part went slightly awry: Affleck said he was working out for his new role as Batman, telling Kerry, "I want to look like you." Then he reached out, seemingly to grab Kerry's bicep, and the whole thing just got awkward. http://abcn.ws/MuAJuV

WHAT WE'RE WATCHING

THE REAL LIFE OLIVIA POPE TELLS THE TRUTHS OF 'SCANDAL'. Before she teamed up with Shonda Rhimes to produce the hit ABC television show "Scandal," Judy Smith kept such a low profile that she didn't even have business cards or a website for her crisis management consulting firm. But today, Smith is firmly in the limelight as the inspiration for the show's main character, Olivia Pope, played by actress Kerry Washington, and told "Politics Confidential" that despite the show's often far-fetched and very fictionalized plots, Washington has accurately captured the essence of the real-life Olivia Pope. "She does an incredible job," said Smith, the co-executive producer of "Scandal." "You want the character, for me, to be someone strong, someone who is very strategic and smart, at the top of her game, and someone who is very passionate about their work and very compassionate toward their clients." For more ABC's JONATHAN KARL's interview with Judy Smith, including what she said fans can expect to see in the second half of Season 3, which resumes tonight on ABC, check out this episode of "Politics Confidential." http://yhoo.it/1mFDRRV

IN THE NOTE'S INBOX

CORY GARDNER ON WHY MARK UDALL IS VULNERABLE. The news that Rep. Cory Gardner, R-Colo., plans to challenge the state's incumbent Democratic Sen. Mark Udall, shook up the political world yesterday. Republican strategist Joe Brettell e-mailed The Note with insights from a recent conversation with the congressman: "Getting a top-tier candidate like Gardner is a win for the NRSC; he is a proven fundraiser who is articulate on the campaign trail. Despite that, Mark Udall remains a formidable opponent, with deep roots in the state and buoyed by a strong set of outside groups in Colorado that have broken Republican hearts before. When I asked in a recent interview why Udall would be vulnerable this year, Gardner highlighted a theme we're likely to hear often this election season: Obamacare. 'He's vulnerable because 335,000 Coloradoans have had their health insurance canceled, because he was a rubber stamp for President Obama and displayed a lack of leadership for the state.' Gardner said. 'Ultimately this boils down to one issue: [Senator Udall's] wholehearted endorsement of Obamacare at all costs.' Gardner's hopes will rest on buyer's remorse from voters that gave the state to President Obama in each of the last two national elections, coupled with more bad news from Washington on the state of the Affordable Care Act. "

WHO'S TWEETING?

@JillDLawrence: Time cover: Steven Brill account of how tech nerds saved @healthcaregov. Can a movie be far behind? http://ti.me/1mFFkrq

@CapehartJ: READ -> Obama to launch major effort to help young minority men http://wapo.st/1fbzV5s via @washingtonpost

@jdickerson: In the fall of 2012, just 24 percent of Republicans backed legalizing same-sex marriage; now 40 percent do. http://www.nytimes.com/2014/02/27/us/politics/despite-rifts-gop-has-election-edge-poll-finds.html?hp&_r=0 …

@JessicaTaylor: My weekly @TheHill column-How the GOP establishment is fighting back & what other races to watch in '14 party wars http://ow.ly/u3AaZ

@jmartNYT: Why @danbalz is a national treasure (con't) > http://m.washingtonpost.com/politics/governors-in-red-and-blue/2014/02/25/3e90e25c-9e46-11e3-a050-dc3322a94fa7_story.html …