UPDATE VIII:Mike Huckabee is next to take the stage.
The American Spectator states the case for "Mike Huckabee ain't dead yet." His stronger-than-expected turnout on Super Tuesday, the departure of Mitt Romney, and his appeal among social conservatives mean he this speech could provide his campaign good leverage for pressing forward into more favorable contests with McCain.

UPDATE VII:President Bush has made his first appearance ever at CPAC today. His speech sought to unite conservatives around McCain as the front-runner, relying on threat of national insecurity and a Democrat in the White House:

"We have had good debates and soon we will have a nominee who will carry aconservative banner into this election and beyond," Bush said. "The stakes in November are high. . . . Prosperity and peace are in the balance. So with confidence in our vision and faith in our values, let us go forward, fight for victory and keep the White House in 2008."

However, White House spokesman Scott Stanzel argued that Bush is staying "studiously neutral" in the race, and that his speech was merely to rally conservatives around the eventual nominee.

Although the President's popularity hit a new low today in an Associated Press poll, the CPAC crowd was ecstatic, chanting "Four more years!"

UPDATE VI: Real Clear Politics has the text of John McCain' speech.

UPDATE V: After facing whithering attacks from conservatives, presumptive GOP presidential nominee John McCain addressed party activists on Thursday at CPAC (after Mitt Romney dropped out). The question remained: How would he be greeted? Conference organizers warned not to boo McCain -- and what happened? There was booing.

Watch to find out why.

Earlier, McCain called Romney a "great governor" and invited Romney's supporters to support his campaign. McCain was accompanied to the event by ex-Sen. George Allen of "macaca" fame, who announced his endorsement.

Andrew Sullivan calls the speech "stirring, honest, forthright, and properly conservative." But some conservatives weren't impressed. "I am hopeful that he will eventually address these issues that conservatives have with him. But he didn't do that," former Majority Leader Tom Delay told the Huffington Post after McCain's speech. "What is his basic position on taxes?"

UPDATE IV: Free Republic has the text of Romney's speech.

UPDATE III: HuffPost's Sam Stein reports on the tears and shock at CPAC over Romney's announcement:

There was a palpable sense of shock both in the audience and among the advisers after Mitt Romney abruptly announced on Thursday that he was exiting the presidential race.

Screams of "no" and tears came from the crowd at the Conservative Political Action Conference in Washington D.C. One attendee lamented the "bombshell."

As the speech was made, Romney's wife sat quietly in the front row. Cameras zoomed in on her mostly expressionless expression, occasionally broken by a slight smile. But not all of the campaign's associates were as composed. Behind the curtains, Bay Buchanan wiped the moist from her eyes. "This is rough," she told the Huffington Post, "very rough."

Romney is reportedly eying a 2012 bid for the White House.

UPDATE II: Mitt Romney is dropping out of the presidential race in his speech at CPAC. From his speech excerpts, Romney says that if he stayed in the race, the terrorists win:

''If I fight on in my campaign, all the way to the convention, I would forestall the launch of a national campaign and make it more likely that Senator Clinton or (Barack) Obama would win. And in this time of war, I simply cannot let my campaign, be a part of aiding a surrender to terror,'' Romney planned to say in a speech to the Conservative Political Action Conference.

''This is not an easy decision for me. I hate to lose. My family, my friends and our supporters ... many of you right here in this room ... have given a great deal to get me where I have a shot at becoming president. If this were only about me, I would go on. But I entered this race because I love America, and because I love America, I feel I must now stand aside, for our party and for our country.''

MSNBC notes that talk host Laura Ingraham, who introduced Romney, blasted McCain in her speech: "She said of the three remaining Republican candidates, she's glad to introduce 'the conservative.' She said it's about 'what you've done for us lately' (read: not in the 80s when you claim to have been a foot soldier for Ronald Reagan). She then added, Let's all 'calm down' for Mitt Romney -- mockingly parroting McCain's language yesterday."

Before quitting the race, Romney dumped at least $35 million of his own money into his campaign.

UPDATE: Huffington Post's Sam Stein reports on Cheney at CPAC:

Vice President Dick Cheney offered an aggressive, unwavering defense of the Bush administration's legacy at the Conservative Political Action Conference on Thursday, after taking the stage to a chant of "Four more years!"

"The President has made the right decisions for the right reasons and he always reflected the values of the American people," Cheney declared, "Would I support those same decisions today? You're damn right I would."

The crowd was adoring. There was a standing ovation as Cheney entered, and a woman shouting: "We Love You!" Attendees clamored for a good "Cheney shot," with one young conservative pumping his fist after catching an unobstructed wide lens take of the Vice President on his camera.

Read the full story here.

CPAC is trying to avoid the embarrassment of having the GOP's likely presidential candidate booed off the stage, Politico reports:

John McCain may have it easier than he expected today when he commandeers the podium at CPAC this afternoon. Conservatives from all over will predictably fill the room to the brim to listen to what the now GOP front-runner has to say, despite a hate/love relationship with the guy.

CPAC it seems, is directing its loyal goers to not boo McCain. They must be more excited that McCain has finally signed on to appear after years of snubs than they want to let on.

During registration last night at the Omni Shoreham a registrant was asking to upgrade his CPAC package and then proceeded to ask what time GOP front-runner John McCain was going to speak today. "Oh good," he said to the response -- answer: 3 p.m. today-- "I hope they boo him out of the room."

"No, no no no no" came the reply from the person registering him. "We've been instructed to tell participants not to boo McCain."

Conservative site Hot Air notes:

Last year, McCain was the only major GOP candidate to skip CPAC. All of the other candidates attended and addressed the conference to make their pitches for conservative support. They were all received warmly. The buzz last year was that McCain was intentionally snubbing conservatives by staying away from the conference, and that left a lot of bad blood that's still lingering. Add in McCain's various non-conservative transgressions over the years plus the fact that he's winning the GOP nomination largely without conservative support and you have the makings of a very interesting moment in the campaign. What will McCain do with it?

The Democratic Party is blasting McCain in advance of his speech: "Panderer In Chief Prepares for CPAC." Politico reports that he's seeking a truce with right-wing activists, and is making a major behind-the-scenes push to win over Sean Hannity and other talk radio hosts.

President Bush is speaking tomorrow morning. It marks his and Cheney's first appearances at CPAC since entering the office. You can click here for a schedule of events.