John McCain predicted the general election race would come down to the buzzer Friday, declaring himself the underdog but quipping that he'd ride to victory in the last "48 hours."

The comment came as new polls show Barack Obama leading nationally and in several key swing states.

McCain may be hoping to reprise his nomination fight, in which he revived his flailing campaign just as primaries began.

"I'm the underdog. I'm behind," the presumptive GOP nominee told reporters in Ohio

"I've got to catch up and get ahead. And I expect to do that about 48 hours before the general election," he said with a laugh.

On a day of heavy focus on the so-called "Unity" rally with Obama and Hillary Clinton in New Hampshire, McCain also fired off accusations at his general election rival.

He criticized Obama for opting out of public financing and refusing to join him for a series of town hall meetings.

"I would meet him anywhere, anytime," he said. "I have kept days open."

McCain later added that the meetings are "very, very unlikely."

FOX News' Mosheh Oinounou contributed to this report.