ORLANDO, Florida (AP) ― Republican presidential candidates Mitt Romney and Rick Perry accused each other in a debate Thursday night of contradicting themselves on issues such as health care and Social Security retirement benefits.

Texas Gov. Perry has overtaken former Massachusetts Gov. Mitt Romney as the front-runner in the race. Seven other candidates also participated, but the Republican contest has largely turned into a two-person race with five months to go before the first nominating contests.

Perry insisted he had backed off “not one inch, Sir” from what he had written in a campaign-season book published a few months ago.

Romney vouched for his own steadfastness moments later. “There are a lot of reasons not to elect me,” he said. “There are a lot of reasons not to elect other people on this stage. ... But one reason to elect me is I know what I stand for. I’ve written it down. Words have meaning.”

Five months remain until the first nominating contests, leaving little time for some of the candidates trying to break free of the pack. Their camps descended this week on Florida, a swing state rich with elderly residents who tend to vote in large numbers.

A poll released early Thursday indicates Florida Republicans slightly prefer Perry, the front-runner, over Romney in their party’s battle to find a nominee to face Obama next year.

Perry runs ahead in national opinion polls, with Romney a close second, and they compete daily for endorsements from members of Congress and other party luminaries in hopes of gaining a permanent edge in the race.

Romney accused Perry of having said that the federal government “shouldn’t be in the pension business, that it’s unconstitutional,” a reference to Social Security benefits.

Noting his rival’s denials, Romney mocked him. “You better find that Rick Perry and get him to stop saying that,” he said.

Perry soon returned the favor, saying Romney switched his position on health care between editions of a book he had published. In one edition, Perry said, Romney advocated expanding to the rest of the country the health care program he signed in Massachusetts.

“Then in your paperback you took that line out, so speaking of not getting it straight in your book, Sir.”

The Massachusetts legislation required residents of the state to purchase health coverage or pay a fine, a cornerstone of the law that Obama won from Congress last year that has inflamed conservative voters across the country.