Republicans said McCain had little choice.

"Every candidate, regardless of whether they're an incumbent or a challenger," said Sara Taylor, a former White House political director under Bush, "one of the fundamental missions is how to set themselves up as the change agent, and John McCain is well equipped based on a long record as a maverick to do that."

And it is true that even vice presidents running as popular presidents leave office have labored to establish their own identities.

"Conventions are always about the next four years, not the last four or eight years," said Ron Kaufman, who was a top aide to President George H. W. Bush. "In the end, whether your party is in power or not, it's about, 'What are you going to do for me for the next four years?"'

Still, even though the elder Bush wanted to slip out of President Ronald Reagan's shadow in 1988 and Vice President Al Gore tried to distance himself from the scandals of President Bill Clinton in 2000, they both used their acceptance speeches to boast of their administrations' records. And neither ran an advertisement like the one McCain did last month declaring, "We're worse off than we were four years ago" — a damning assessment echoing Reagan's own attacks in 1980 on President Jimmy Carter.

By the time the convention here was about to get under way, McCain almost sounded like a speaker at an Obama rally. "I promise you, if you're sick and tired of the way Washington operates, you only need to be patient for a couple of more months," he told supporters in O'Fallon, Mo., on Sunday. "Change is coming! Change is coming! Change is coming!"

McCain continued the mantra in his speech Thursday night. "Let me offer an advance warning to the old big-spending, do-nothing, me-first, country-second Washington crowd," he said. "Change is coming."

Just hours earlier, Palin sent an e-mail message to supporters promising that "John McCain and I are ready to shake up Washington, ready to challenge the status quo."

McCain has been a strong supporter of Bush on the Iraq war and has embraced other aspects of the administration's agenda, including tax cuts, providing plenty of ammunition for the Democratic argument that his election would amount to a third Bush term.

Still, he might be better positioned to pull off the change argument than any other Republican, given his reputation for independent politics and periodic scraps with Bush.

What Republicans will try to argue is that Obama represents the wrong kind of change and that McCain has a proven record of pushing for reform.

"They would have you believe that this election is about change versus more of the same," Giuliani told the delegates, "but that's really a false choice, because there's good change and bad change."

Voters have 60 days to decide which is which.