Party affiliation has always been a fleeting thing for Michael Bloomberg. When the billionaire and lifelong Democrat ran as a Republican for mayor of New York City in 2001, his conversion had nothing to do with epiphany and everything to do with expediency (as the GOP candidate, he’d face an easier primary field and could spare himself the labyrinthine nominating process he'd face on the Democratic side). As mayor, he has been the quintessential air-quotes Republican—supporting gay marriage, promoting radical measures to make the city greener and staying as far away from President Bush as he possibly could. Term-limited in New York, the mayor's aides have actively talked up the possibility of his running as a third-party presidential candidate in recent months. Today's news that Bloomberg was changing his party status from "Republican" to "unaffiliated" is hardly Earth-shattering. It was only a matter of time before he and the Republican Party stopped pretending like their marriage could be saved.
But while Bloomberg's departure is not unexpected, neither is it welcome news for his fellow New Yorkers Hillary Clinton and Rudy Giuliani—the front runners, respectively, for the Democratic and Republican nominations in 2008. Sure, as a diminutive, divorced, Jewish New Yorker, Bloomberg is a long-shot as a presidential candidate—even if he is willing to put $1 billion of his vast personal fortune toward the cause. A hypothetical Bloomberg challenge conjures a number of interesting questions. (Who would carry New York?) But beyond the delicious subplots, "Mayor Mike" could play a determinative role in a general election by peeling off independent voters in swing states.
But which party does he peel them away from? With high unfavorable ratings among independents, moderates and Republicans, Clinton can hardly take the middle for granted should she win her party's nomination. Bloomberg may prove an attractive choice for centrists who've tired of the Bush-era Republican party but aren't anxious to relive the Clinton years. Giuliani meanwhile, has staked much of his candidacy on his electability—the idea that he could actually give Democrats a run for their money in Midwestern and Northeastern states. But a kinder, gentler former New York mayor competing with Rudy for Republican and moderate votes in those states might soften Rudy's Blue state surge.
Other candidates could also feel the Bloomberg effect in a general-election fight. John Edwards has made a strong pitch for his party's populist wing. Should he win the Democratic nomination, pro-business voters in the middle might view a Bloomberg vote as a protest against both Bush-backing Republicans and labor-pandering Dems. Barack Obama's campaign is centered around the idea he would introduce a new, different kind of politics. Whatever you may think of it, Bloomberg's candidacy would certainly be new and different. On the right, Mitt Romney has taken conservative positions on every major social issue in the hopes he will emerge as the choice of Christian conservatives in the primary. Should he win the nomination, he's counting on moderate voters remembering he was the governor of liberal Massachusetts for four years. But that pivot could prove harder with a viable, socially moderate independent candidate in the race. John McCain and Fred Thompson's aides talk up their candidates' appeal to a broad swath of voters as evidence they can lead the GOP out of troubled times. But that appeal may well be limited as long as McCain and Thompson refuse to break with Bush on the unpopular war in Iraq.
Still, none of the candidates will probably lose much sleep over Bloomberg's announcement tonight. They've got more immediate problems to deal with. On the day Bloomberg left the Republicans behind, both Clinton and Giuliani were playing hard for their partisan base—she at a union forum in Washington and he at a Houston fundraiser. With contentious primaries in both parties, Bloomberg can expect to spend the next seven months stretching out in the middle, all by himself.