Former Massachusetts Gov. Mitt Romney (R) maintains his status as the nominal front-runner for the GOP presidential nomination, according to a new poll released Wednesday.

But that status might be threatened by the entry of three Republican heavyweights — Texas Gov. Rick Perry, former Alaska Gov. Sarah Palin or former New York City Mayor Rudy Giuliani — into the race.

Romney leads among announced candidates; 27 percent of Republicans and Republican-leaning independents said they would support Romney in a new Gallup poll, followed by 18 percent for Rep. Michele BachmannMichele Marie BachmannKlobuchar urges CNN town hall audience: 'That's when you guys are supposed to cheer, OK?' Michele Bachmann praises Trump: Americans will 'never see a more godly, biblical president' Will Biden lead a 'return to normalcy' in 2020? MORE (R-Minn.) and 11 percent for Rep. Ron Paul (R-Texas).

But Romney's status as the front-runner looks softer when Perry, Palin and Giuliani are included in the poll. Romney loses support if even one of those candidates is included in the polling.

Romney's support drops to 17 percent when all the candidates and potential candidates are included in the poll — good enough for first, but only by a two-point margin. Fifteen percent would back Perry, 12 percent would back Palin, and 11 percent each would support Giuliani and Bachmann.

Those figures say just as much about Romney as they do about the three prospective late entries into the campaign. The former Massachusetts governor has consistently led the field in polling of the race for the GOP nomination, but never by a commanding amount. He enjoys wider margins in some state-by-state polls.

Of course, it might come to pass that none of these would-be Romney challengers will enter the race, or necessarily be successful when they do. Perry appears to be the candidate closest to entering the race, having reached out and prepared a campaign over the past few weeks. Palin said Tuesday night that she's still looking at it, though observers are pessimistic about her likelihood of entry. Giuliani has said he's still deciding, but his decision to host the "Mob Week" special on AMC next month has spurred murmurs that he won't run.

But there appears to be room and appetite for a new candidate in the race, not necessarily as an "anti-Romney" so much as an alternative voice.

By contrast, the poll is especially worrying for candidates like former Minnesota Gov. Tim Pawlenty (R) and former House Speaker Newt Gingrich (R-Ga.). Pawlenty's garners 2 percent in the full list of candidates, a number that doubles to 4 percent among announced candidates. Three percent support Gingrich against the full list; the former Speaker scores 7 percent among announced candidates.

The poll, conducted July 20-24, has a 4 percent margin of error.