Still, one can at least imagine the president standing at 47 percent or 48 percent on Election Day, something that seemed flatly outside the realm of possibility five months ago. This change would narrow our playing field down to seven Democratic seats and two or three Republican seats.

Next, the four “red state” incumbent Democrats would have to win. It’s unlikely, but hardly implausible. No one really knows what is going on in Alaska, a quirky state where polling is notoriously unreliable. The GOP’s candidate field is relatively weak in North Carolina. Recent polls have shown renewed vigor for Mark Pryor in Arkansas (though many of those polls are done on behalf of groups with an agenda), and Louisiana’s Mary Landrieu survives tough contests every six years. None of these incumbents is in great shape, but no one is terminal either.

Next, Democrats would have to win one — preferably two — of the three open seats. This is . . . tough. Right now Republican candidates are above 50 percent in South Dakota, Montana and West Virginia. But the truth is that those last two states are much less heavily Republican than their presidential numbers make them seem. With Max Baucus’ appointment as ambassador to China, Republican Steve Daines finds himself in a race against an incumbent. Democrats also have a credible candidate in West Virginia in Secretary of State Natalie Tennant. I’ll just put it this way: If I went into a coma tomorrow and emerged from it the day after the election, South Dakota is the only one where I’d be truly bowled over if the Democrat ended up winning (assuming an improvement in the president’s standing).

The final step would require an assist from Republicans.