A Democratic primary challenge to President Obama in 2012 seems unlikely at this stage in his presidency, but falling poll numbers, apprehension over potential Democratic losses in the midterms, and a Gallup poll released Thursday suggests that the prospect of a primary challenge is not completely outside the realm of possibility.

A Gallup poll of registered Democrats conducted September 25-26 shows President Obama leading Hillary Clinton for the Democratic nomination by 15 points. Obama receives 52 percent to Clinton’s 37 percent with 10 percent remaining undecided. While this seems like a solid amount of support for the President, that fact that nearly 40 percent of respondents suggest that they would like to see a change in the Democratic Party’s nominee may be troubling for the White House.

But Clinton surely remembers a time not that long ago when she was polling well ahead of the insurgent Obama candidacy. Gallup/USA Today had Hillary Clinton leading Obama by 22 points in December, 2007 – less than 7 months before the last delegates in the prolonged Democratic nomination process were counted and the nomination was secured for Obama. At times, Clinton led Obama in polls by more that 30 points.

Clinton has indicated she has no intention of challenging the President for the nomination. In July, 2009 she told NBC’s David Gregory on Meet The Press the political equivalent of “no.” “I have absolutely no belief in my mind that that is going to happen,” Clinton stressed. 

Interestingly, Obama does better in the recent Gallup poll with all respondents, men, women, college graduates, non-college graduates, but Clinton bests Obama among conservative Democrats. Among these voters, Clinton receives the support of 48 percent, compared to 41 percent who favor Obama. As disappointed the liberal base of the Democratic Party is with the administration, they may not be ready to abandon Obama just yet.

It is worth noting that, historically, most Democratic presidents are challenged in their reelection primaries, with Bill Clinton’s 1996 campaign being the exception. In 1980 President Carter was challenged by Sen. Ted Kennedy, but managed to win after a costly intraparty feud. Had Lyndon Johnson not opted against seeking a second term, he would have been challenged by Sen. Robert Kennedy and Sen. Eugene McCarthy. Gov. George Wallace would have likely challenged John F. Kennedy, as he did Johnson in 1964. Sen. Richard B. Russell challenged Harry Truman in 1948. The only elected president to lose a primary nomination for a second term, however, was Franklin Pierce, a Democrat himself, in 1856.

A caveat to historical precedents for primary challenges is that delegates select the presidential nominee, not voters, and only after the 1968 Democratic convention in Chicago did direct election of delegates begin. Even so, those who remember the debates in the early spring of 2008 about delegate counts and “super delegates” will understand that party power brokers, and not necessarily the popular vote, have significant influence over the presidential nomination process.

So will Hillary go for it? The answer is a definitive “who knows?” The 2012 nomination process is an eternity away. If Clinton still harbors presidential ambitions and Obama looks as vulnerable today, it is possible that she would go for it rather than see a new Republican president sweep the office away for another 8 years. This Gallup poll gives her supporters some hope that 2008 may not have been their last shot. Of course, if she is not interested in the presidency, there is probably another Democrat somewhere that would be.

Noah Rothman is the online editor at C&E. Email him at nrothman@campaignsandelections.com