Kasie Hunt

Associated Press

DENVER, Colo. (AP) —If Republican Mitt Romney stumbles during Wednesday’s presidential debate, it won’t be for a lack of preparation.

The Republican presidential nominee has spent at least eight days of the past month getting ready for the three debates against President Barack Obama. He’s holed up for hours on end with briefing books, top aides and his sparring partner, Ohio Republican Sen. Rob Portman, often at the expense of campaigning.

Romney began intense sessions Sept. 4 at an adviser’s home in Vermont. Those ran for three days and drew the campaign’s entire top echelon to a remote resort in the mountains. A few weeks later, top aides flew to Los Angeles for more practice. Romney has held debate practice at his Boston headquarters, and he spent part of last weekend at the Back Bay Events Center, where the auditorium holds 1,100 people.

The reasons are clear: The stakes are enormous given that Romney trails the president in surveys in key states and national polls favor Obama in a close race, and the debates are one of the Republican’s final opportunities to shift the dynamics of the race. Millions of people are likely to watch the debate at the University of Denver, as well as two more slated later this month in New York and Florida. And Romney is looking to use the forums to put Obama on his heels in the home stretch.

Both campaigns have been working to lower expectations.

Romney’s team has argued that Obama is a gifted speaker who has participated in general election presidential debates before, while Romney will engage in his first presidential fall matchup. Romney aides overlook the fact that he has a wealth of other debating experience, given that he participated in 19 primary debates during 2011 and 2012 — more than 30 hours of time onstage with as many as 7 other candidates at a time — and roughly the same number during the 2008 GOP primary race.

Romney typically emerged from those debates, usually 90 minutes with multiple opponents, as the clear leader. His performance in Jacksonville, Fla., helped seal his primary win there over former House Speaker Newt Gingrich — though Gingrich had challenged him in an earlier debate in Tampa.

Romney rarely, however, has gone one-on-one against a political opponent, a format that leaves little time for contemplation in between answers to questions.