Sarah Palin could win the presidency in 2012—that’s what Frank Rich said in the New York Times on Sunday—but not in a two-person head-to-head race. For Palin to beat Obama, a third-party candidate would have to run, and take votes away from Obama. 

And we have a potential third-party spoiler, Rich says: New York Mayor Michael Bloomberg. He’s got the money, and he’s got the ambition. He ran for mayor as a Republican in 2006 but changed his registration the next year and won re-election as an independent.

Obama’s hope is that Republicans will pick Palin in 2012. The latest CNN poll shows him beating her 52-44 percent, but losing to Mitt Romney 50-45 and to Mike Huckabee 52-44. But those are all two-person races.

According to the Palin-wins scenario cited by Frank Rich, Bloomberg takes away from Obama the votes of moderates who think he’s been too liberal, who think the country needs a president who’s truly a centrist. Obama loses New York, New Jersey and Connecticut to Bloomberg, and loses moderate votes that gave him the majority in 2008 in key industrial states—Pennsylvania, Ohio, Indiana–where the white working class never liked Obama anyway, but gave him a chance in 2008. In 2012 they go to Bloomberg and Palin carries those states. Palin takes office in January 2013.

The Bloomberg-as-spoiler scenario may seem unlikely, but Obama is already worrying about it. He’s been courting Bloomberg big time, as John Heilemann pointed out in New York magazine: Obama invited Bloomberg to play golf when he was vacationing on Martha’s Vineyard; he floated Bloomberg’s name as a potential Treasury secretary, he made a big deal of sending Joe Biden and Tim Geithner to “seek his economic counsel.”  

But how likely is it that Palin would be the beneficiary of a Bloomberg candidacy? Seems to me it’s more likely that Bloomberg would win the votes of Republicans who think Palin is a disaster, but couldn’t bring themselves to vote for Obama. They’d go for Bloomberg, who would thus serve as a spoiler for the Republican candidate rather than the Democratic one.

Evidence for that scenario comes from anxious Republicans, especially from Haley Barbour, Republican governor of Mississippi, who urged Bloomberg not to run. He told CNN on Friday that a third-party bid by Bloomberg would be "the best thing that can happen to President Obama" because he’s take votes away from the Republicans.

But will Bloomberg run? He considered running in 2008. He’s “surrounded by people urging him to run,” according to Heilemann. Reports are that he sees 2012 as his last chance, because he will be 68. 

The hard part for any third-party candidate is getting on the ballot in all fifty states. But there’s already a potential path for Bloomberg, called Americans Elect. It has a website promising a third-party candidate who would represent “the vital center of American public opinion.” According to Heilemann, it’s funded by “a wealthy private investor,” Peter Ackerman, who has already put $1.5 million into the project.

If the economy doesn’t recover, if Obama doesn’t rebound in the opinion polls and if the Republicans pick Palin, Bloomberg could conclude that neither party has what American voters want and need. He could spend a billion dollars of his own money on a campaign, or even two or three billion. No one is sure what would happen—that’s why both Haley Barbour and Barack Obama are trying to keep Bloomberg from running.