Rick Perry still holds a sizable lead over Mitt Romney among Republican primary voters, but Romney does better among the general electorate, according to the latest Gallup Poll.

The poll, released Monday, shows Perry with 31 percent support and Romney with 24 percent support -- a 7-point lead for Perry. That's down from mid-August, when polls showed Perry with a double-digit lead over Romney, but it is still significant, especially because voters' preferences are solidifying and the number of undecided voters dwindling.

Ron Paul came in third with 13 percent support. Michele Bachmann, once considered a frontrunner, had just 5 percent -- a precipitous drop from her 13 percent in July and 10 percent in August. She is now tied with Newt Gingrich and Herman Cain near the bottom of the pack. The only candidates behind her are Jon Huntsman and Rick Santorum.

The only way she can get back in this race is to somehow win Iowa, Ed Rollins, a Republican strategist who recently resigned as Bachmann's campaign manager, predicted in an interview with USA Today, which co-conducted the poll with Gallup.

In a head-to-head contest, with the other candidates eliminated, Perry beat Romney by 10 points, 49-39. He also led Romney among registered Republicans and independents who leaned Republican -- the key demographics in the primary elections.

But Romney led Perry among swing voters, whose support will be crucial in the general election. And in hypothetical matchups with President Obama, the Gallup poll found that Romney would win, 49-47 percent, but Perry would lose, 50-45 percent.

Interestingly, despite those numbers, the majority of Republican primary voters still believe Perry has the best chance of defeating Obama.

The eight Republican candidates will have their fourth debate of the month on Thursday in Orlando, Fla. The previous debates were held in Columbia, S.C., Simi Valley, Calif., and Tampa, Fla.