It's no secret--at least to people who are paying attention to this year's presidential contest--that Hillary Clinton's case for the Democratic nomination has grown, well, thinner over time. Her first hope was to catch rival Barack Obama in the race for pledged delegates with wins in big states like New York, California, Ohio and Texas, but it quickly became clear to everyone involved--including her staffers--that Obama's massive caucus-state blowouts had made it mathematically impossible for the New York senator to erase his 150-delegate lead by the end of regulation. Next, her advisers turned to the popular vote, arguing that a win there might give the party leaders known as superdelegates a reason to choose her over Obama. The only problem? Now that effort to schedule revotes in Florida and Michigan have collapsed, the vox populi arithmetic appears nearly impossible as well. With 10 states (or an estimated five million people) left to vote, Clinton would need an unprecedented "57 percent to 43 percent overall victory, including expected defeats in states counting for well over 1 million votes," to surpass Obama in the ballot battle, according to the Politico's Ben Smith. Snowball, meet hell.

Clearly, the Clintonites could use a new type of calculus. Enter Sen. Evan Bayh of Indiana. Last night on CNN "Late Edition," Bayh, an avid Clinton backer, suggested that superdelegates consider "who carried the states with the most Electoral College votes" when choosing which candidate to support. "[It] is an important factor to consider because ultimately, that’s how we choose the president of the United States,” said Bayh. The underlying principle is nothing new. As Amy Chozick reports in today's Wall Street Journal, "the Clinton campaign has been using the big-state argument on and off since Super Tuesday" to plead that, while Obama has won among "affluent voters in caucuses and primaries in states with small populations of Democrats -- such as Idaho and Wyoming -- and among African Americans in Republican states unlikely to turn blue in November," Clinton's victories "in big states such as California and Ohio make [her] a stronger candidate to defeat presumptive Republican nominee Sen. John McCain." But Bayh's Electoral College equation superimposes a layer of tidy quantifiablility over the whole argument, which is supposed to make it sound more convincing. Numbers, good. Subjectivity, bad.

But is Bayh's calculus actually convincing? Logically, no. Practically? We'll see. The actual electoral vote tally--219 for Clinton, not counting Florida and Michigan, versus 202 for Obama--is pretty meaningless. As Slate's Jeff Greenfield has argued, it's stupid to assume that primary contests can provide a guide to the fall campaign; there's no chance that Obama will lose California (or New York) next November just because Clinton beat him there on Super Tuesday. That said, Bayh's equation is designed to symbolize a subtler measure of strength. As everyone knows, neither Clinton nor Obama will reach the magic number of delegates by the end of primary season in June, meaning that only the 330 or so remaining uncommitted superdelegates can put someone over the top. And despite what Team Obama says--that supers are morally bound to choose the candidate with the most pledged delegates--there is, in fact, no such rule. Superdelegates can do whatever the heck they want. The important thing for Bayh, then, isn't that Clinton leads Obama in overall "electoral votes"--it's that she has trounced (or is expected to trounce) him in the key, big-ticket electoral swing states, where she now runs stronger against McCain in local opinion polls. In Ohio, for example, Obama loses to McCain by an average of seven points; Clinton edges the Arizona senator by an average of 0.3 percent. It's a similar story Pennsylvania, where Clinton averages two points better than Obama versus McCain. In Florida, she leads Obama by four. Most of these results are within the margin of error, and, again, November is a whole different ballgame. But Bayh (and, by extension, Clinton) is hoping that at the end of primary season, the supers will do the "electoral math" and decide that Clinton, who runs stronger among blue-collar Dems and Latinons, has a better chance of retaining Pennsylvania and recapturing either Florida or Ohio--meaning that she's more, you know, "electable."

Like it or not, it's the sacred right of the superdelegates to make such a decision. Do I expect them to buy Bayh's new arithmetic? Not really. The vast majority of these poo-bahs are politicians, and the last thing they want is Obama's half of the party accusing them of overturning "the will of the people." But the electoral equation is Clinton's only remaining rationale--and there's no reason to think she won't keep hammering it until the last dog dies. Or at least until another one comes along.

UPDATE, 3:40 p.m.: The New Republic's Jonathan Cohn has a smart take on the subject:

I am not prepared to dismiss entirely the idea--floated on a few occasions by Clinton supporters--that she might be stronger in the states that matter most for the general election. If Obama's problems with Latino and blue collar whites persist, he might have a harder time than she would in Florida, Missouri, Ohio, and Pennyslvania -- all states where Pollster.com has Clinton running stronger right now. (Obama also seems to put New Jersey into play.) That's a lot of electoral votes to cede. Even if you assume, as some Obama supporters do, that he'd run stronger in the Pacific Northwest and Mountain states, she'd come out ahead. The huge, elephant-size caveat here is that predicting November matchups this far out is very hazardous business. The new Gallup poll suggests Obama has already made up much of the ground nationally that he lost becuase of the Reverend Wright controversy.  And if Obama supporters decide to stay home on election day because they decide Clinton came upon the nomination illegitimately, I assume the poll numbers we're seeing now will look a lot worse for her. So, as I've said many times, the best strategy is probably not to weigh electability much--if at all. (And that goes for the superdelegates, too.)

Sound advice. But as the Atlantic's Marc Ambinder notes, "John Edwards, Al Gore, Nancy Pelosi, Harry Reid – if these folks came together and threw their weight behind the nominee, Hillary Clinton would probably drop out by the end of the week. But the party elders have in some cases explicitly abstained from making such a determination because in their minds, the racetrack is open and the horses, to beat that metaphor to death, are still trotting around." It's up to the superdelegates to decide--and they don't think it's over. Neither should we.