May 13, 2008 -- Sen. John McCain, taking a victory lap as the presumptive Republican nominee, happily poked fun at his only remaining opponent.
Asked during an appearance on "The Daily Show" last week which of the two Democratic nominees he preferred to run against in the general election, McCain quipped, "Ron Paul."
But Paul might get the last laugh during McCain's coronation at the party's convention in early September.
McCain's nomination may be certain, but he finds himself pressured by different wings of the conservative movement -- from the libertarians and the anti-war activists, to social conservatives and evangelical voters.
In recent primaries, as many as 25 percent of Republican voters chose a different candidate, with many pulling levers for Paul and former GOP candidate Mike Huckabee, who snagged 27 percent of the vote in the Pennsylvania primary.
A similar phenomenon also occurred in 2000, when 33 percent of Republicans voted against Bush in the Colorado primary though Bush was the presumed nominee by then.
Paul's grass-roots movement of enthusiastic supporters is reportedly planning a minirebellion at the convention to push its anti-war, anti-tax agenda.
In state conventions in Maine and Nevada, Paul's forces battled McCain's delegates to the brink. While they won't have the muscle to challenged McCain in the national convention, they can be an annoying sideshow when the spotlight is supposed to be solely on the candidate.
Huckabee has endorsed McCain, but some of his evangelical supporters remain skeptical about McCain's claim to be a social conservative.
Virginia conservative Michael Farris, the chancellor of Patrick Henry College, reportedly promoted an Obama presidency as a biblical punishment for Republican sins, which would allow the party to regroup and come back under the leadership of Huckabee in 2012. Farris denied that he ever suggested such a thing during an interview with ABCNEWS.com.
And former GOP Rep. Bob Barr, who won acclaim in conservative circles for leading the drive to impeach President Clinton, just announced his run for the presidency on the Libertarian Party ticket.
The party commands few votes, but Barr has the potential to draw away Republican voters and be a spoiler in battleground states as Ralph Nader was accused of doing to Democrats in the 2000 election.
Though McCain's nomination at the convention is assured, it may not be a love fest and that concerns Republicans who are warily eying a resurgent Democratic Party that has galvanized millions of new voters.
"What's happening with Ron Paul cannot be ignored by John McCain," said Greg Mueller, a Republican consultant not affiliated with any campaign.
"You need every vote, whether it's a social conservative, a tax conservative or a national defense conservative. Like the social conservatives, if that vote had been ignored, George Bush would not have made it in 2000. … They have to be excited, energized to get other people to vote."
A spokesman for the McCain campaign emailed: "We're very pleased by the overwhelming support that John McCain is receiving from all levels of the Republican Party, something that has not been seen after other open primaries in the recent past, and are now mobilizing them towards the convention and the get out the vote operation in the general election in November."
The chairman of the Republican National Committee, Mike Duncan, had a private meeting with Paul in April to discuss the future of the party but no decision has been made yet on speaking roles at the convention, according to an RNC official.
Virginia conservative Farris says the lack of enthusiasm among some social conservative leaders should worry McCain.
"He's not gone out of his way to win over people concerned about his record," he said. "If he doesn't, he's asking for more dissension. He needs to solidify that base. If he dampens the enthusiasm of even a small percentage, in a close election that could be crucial."
Farris notes that Republican voters need positive reasons to vote for their candidate. "Unfortunately, it's coming down to whether you like [Democratic Sen. Barack] Obama or not. We can't win if it's just based on negative reasons not to vote for the opposing candidate."
Farris also denied a story by syndicated columnist Robert Novak reporting that he promoted an Obama candidacy as a biblical justification.
"I've never said or heard such a thing," he said, noting that he probably will vote for McCain. "I don't talk in terms of Old Testament plagues. One thing we learn is that they're undesirable so the fact that I would desire something like that doesn't make sense."
Huckabee posted a denial on his political action committee's Web site, reiterating his support for McCain and stating, "The nonsense that I want Obama to win this year so I can run in 2012 is absurd. I love my country more than my own ambition."
As for Paul, although he only has collected 19 delegates so far compared to McCain's 1,413, he plans on bringing them to the convention and stressing his limited government agenda, which includes abolishing the Federal Reserve and the Internal Revenue Service.
Paul is also insisting on a speaking opportunity at the convention, which the GOP has yet to offer.
As for Barr, his spokesman says that the Libertarian Party typically attracts more voters from the Republican side.
"Any third party can be a potential spoiler," Barr spokesman Andrew Davis says. "Ross Perot did it in 1992. Our party competes just like any other party does."