Beyond the Dome

The rush of superdelegates toward Barack Obama is nothing if not well-choreographed. It had seemed to stall out early this afternoon, but in the last hour or so, it has picked up so much speed that Obama is now well within range of locking down the nomination tonight.

You don't even have to believe the Associated Press, which reported that its own tally had Obama winning the nomination earlier this afternoon. Its count included private commitments, which even the Obama campaign isn't counting in its own estimates.

As of around 5:30, the campaign said Obama was 12 delegates short of the nomination -- well within range of the approximately 15 delegates he's expected to win in the Montana and South Dakota primaries tonight. The latest count includes Rep. Maxine Waters of California, a former supporter of Hillary Rodham Clinton who just announced she's switching sides.

It also counts a group of 10 pledged delegates, all supporters of former Sen. John Edwards, who announced shortly after 5:00 that they were switching to Obama.

Democratic Sen. Claire McCaskill of Missouri, one of Obama's closest allies, just told me that there's not likely to be any large group of Senate superdelegates who will endorse Obama tonight (though the Montana senators are a possibility). Instead, she predicted that more non-congressional superdelegates will endorse Obama between now and 10 p.m., making such a mass move by Senate superdelegates unnecessary.

After that, McCaskill said, "I think what you'll see is a rapid coming together of everyone over the next two to three days."