Challenged: McCain's Conservative Authenticity

A smiling Sen. John McCain, R-Ariz, arrived at Omni Shoreham Hotel in Washington, D.C., for the Conservative Political Action Conference, only minutes after his vanquished rival, former Massachusetts Gov. Mitt Romney, had left. With Romney's sudden exit from the race, McCain became, in every sense but officially, the Republican presidential nominee.

Former Arkansas Gov. Mike Huckabee has vowed to carry on the fight, but the sense now was that it would only be a matter of time before he, too, bows out. McCain's chore today — and likely for months to come — would be to convince conservatives, who view with suspicion and hostility, that he is one of them. It will be a hard sell for some.

When McCain entered the hotel lobby, surrounded by supporters waving blue and white campaign posters, Laura Morales of Texas stood off to the side, shouting "Rino! Rino!"

Rino? "He's a Republican in name only," she said. "He calls himself a Republican, but he's distanced himself so far from the party that he doesn't really stand for what conservatives really believe in."

Her friend, Ruth Malhotra, a Georgia Tech undergraduate, chimed in, "He's betrayed conservatives. He will not get my support."

Inside the ballroom where McCain would speak, Ryan Galloway, of Dallas, Texas, a Romney supporter, was a bit more open to the idea of voting for McCain.

"He's going to have to come to us today and say, 'I am a true conservative, these are my values, and I do now believe in lower taxes, go through the basics, and hitting at core values of conservatives," he said.

"Will saying, 'I am a conservative' be enough to make up for the qualms of conservatives," he was asked.

At first, he said, "No." But he quickly added, "We'll just have to see later. It's going to be tough for him to pull if off, but as long as he makes an authentic effort, I guess I'll be able to support him."

These are the kind of people who McCain must convince and convert. His speech was a delicate dance. He laid claim to an overall conservative record, but he tried to do so without apologizing for the times he strayed from conservative orthodoxy.

"Even if you believe I have occasionally erred in my reasoning as a fellow conservative," McCain said, "you will still allow that I have, in many ways important to all of us, maintained the record of a conservative."

Once again, McCain invoked the name of that conservative icon, Ronald Reagan.

"I am proud, very proud, to have come to public office as a foot soldier in the Reagan Revolution," he said. "And if a few of my positions have raised your concern that I have forgotten my political heritage, I want to assure you that I have not."

Almost as a warning of what the alternative is, he repeatedly raised the specter of a choice between himself and the Democratic alternatives.

"Senator Clinton and Senator Obama want to increase the size of the federal government," McCain told voters. "Senator Clinton and Senator Obama will raise your taxes."

Did he convince those skeptics? One small sign of progress was that he wasn't booed. Last year, when he didn't show up, his name was lustily booed by the crowd.

Some conservative leaders said McCain will have to build his ties to the conservative wing of the party. That will take time.

"What [McCain] needs to do is building credibility over time, and if he does that, I think he can solve 98 percent of his problem," said David Keene, president of the American Conservative Union.

"He'll never get everyone he's fought with, on board. If he does nothing, a lot of people will be on board, anyway, because he'll be the [GOP] nominee, and they'll say that's the way it is. But that's not going to be enough. We're probably going to have a close national election, and he needs an energiz-able base that he can trust."

ABC News' Jon Garcia contributed to this report.