Now, struggling under a raft of retirements that has dimmed their chances of regaining control of the House and Senate, Republicans are coming to terms with the idea of the Arizona senator at the top of their ticket in November.
McCain, the Republican presidential nominee-in-waiting met Wednesday morning with House Republicans, a group dominated by conservatives who have been suspicious of his moderate positions on some issues and willingness to work with Democrats.
It was, as McCain said, "a spirited and good discussion."
GOP leaders, conservatives all, appeared with him afterward to declare they would rally together, acknowledging the party must unite if it hopes to match the enthusiasm generated by Democrats Barack Obama and Hillary Rodham Clinton.
"Clearly, I've had some disagreements with Senator McCain over the years," said Republican leader John Boehner, an Ohio congressman. "But I've got to tell you, I've watched this presidential race unfold, and I've watched John McCain be a strong advocate for the principles I believe in."
Like Boehner, many rank-and-file Republicans are looking at the bright side.
"I thought he reached out too much to Democrats, but he has a broad appeal," said Kansas Republican Rep. Todd Tiahrt, a staunch social conservative. "And perhaps I was just limiting my vision to something that was too narrow."
Tiahrt said McCain's loss last Saturday in the Kansas caucus and Louisiana primary to former Arkansas Gov. Mike Huckabee sent a "strong message that conservatives don't want to be forgotten."
But he said there are ways McCain can reach out to conservatives. One way would be who McCain chooses for the vice presidential slot.
"There are good vice presidential candidates that may help bridge that gap," Tiahrt said, mentioning Minnesota Gov. Tim Pawlenty or Mississippi Gov. Haley Barbour as possible conservative choices. Barbour was re-elected last November.
Rep. Lynn Westmoreland, R-Ga., said conservatives will come around, given the choice on the other side.
"Conservatives who've held reservations about McCain are going to feel different, perhaps, when the contrast is drawn between him and either Hillary Clinton or Barack Obama," he said. "Both of the Democratic candidates would do a good job at unifying our base."
However, neither Westmoreland nor Tiahrt has endorsed McCain. In fact, thus far McCain has collected endorsements from about 40 of the 198 House Republicans; in the Senate, he is endorsed by about 20 of 49 Republicans.
While McCain has faltered in "red" states that vote Republican, such as Kansas, moderates see him as extraordinarily helpful in "blue" states that trend toward Democrats.
"He appeals to independents, so John McCain can carry Minnesota, he can carry Maine, he can carry Oregon, he can carry New Hampshire," said Minnesota GOP Sen. Norm Coleman. "From that perspective, having him at the head of the ticket is a great thing."
Connecticut Republican Rep. Christopher Shays, who like McCain has clashed with party leaders, noted that McCain campaigned for him in tough re-election fights in recent years, helping boost support among independent voters.
"He's not intimidated by anyone, including Rush (Limbaugh)," Shays said of the conservative radio talk show host who has warned that choosing McCain as the Republican standard-bearer would destroy the party. "He's an independent thinker, he's got a Teddy Roosevelt streak in him."
For his part, McCain promised to work hard to elect Republicans to the House, and allowed that Democrats have generated more enthusiasm among voters to date.
Yet the forces brewing in congressional races are bigger than the Republican nominee, said Duke University political scientist David Rohde.
"I think the Republican problem at the congressional level is money, candidates and open seats; it's not McCain," he said.
Tiahrt said predicted that conservatives in Kansas and other places will come around when it comes down to it.
"He's going to be seen by the Republicans as our guy," Tiahrt said. "There is no desire for people to stay home in this election. People are going to get out and vote, and they're going to vote for John McCain."
