The latest Diageo/Hotline poll illustrates the dilemma Democratic voters are facing. Barack Obama is now leading Hillary Clinton 50% to 38%, a seven-point increase for him and a seven-point drop for her since the February poll. However, when stacked up against John McCain, Obama now trails 44% to 46%, a ten-point swing for McCain since last month’s poll.

In short, the Democrats are embracing a candidate who is doing worse over time against McCain. Is that the Wright affair gnawing away at Obama’s electability? Or are momentarily disaffected Clinton voters expressing frustration to pollsters? We don’t know yet. Whatever the cause, it seems that Clinton’s analysis of the situation (Obama may not match up well against McCain) is better than her solution (Choose me instead). She is simply not an acceptable option for most Democrats.

This problem could worsen over time. If by June Clinton has not moved appreciably closer to Obama in either the delegate count or the popular vote, but Obama is doing worse and worse against McCain, what will the Democrats–and especially those superdelegates–do?

Throwing Obama overboard would be immensely difficult: it risks an open revolt and potentially irreparable damage to the party’s hopes of unifying for the general election. But would the Democrats simply take the plunge with a candidate who would be a losing bet against McCain?

For those who like intrigue and far-fetched plots, this would be the Al Gore moment. For the good of the party, superdelegates put his name in play and he rescues the Democrats from electoral disaster. Does it seem too far-fetched? Yes. But less than it used to.