Ordinarily, presidential endorsements from two former red-state senators, neither of whom are especially high-profile right now, wouldn't be especially newsworthy, but I think today's announcement that Sam Nunn and David Boren are backing Barack Obama is a little more interesting than most.

The Obama campaign sent out a press release, noting the endorsement, and adding that both Nunn and Boren have accepted Obama's invitation to serve as advisors to his National Security Foreign Policy Team. With Nunn having been a chairman of the Senate Armed Services Committee, and Boren's record as the longest-serving chairman of the Senate Intelligence Committee in history, these guys carry some institutional heft.

There are a couple of different angles to this. Josh Marshall emphasizes the fact that Nunn is from Georgia, and Boren is from Oklahoma, which speaks to Obama's appeal to red-state and rural Dems.

I haven't seen a comprehensive analysis in a while, but it seems Obama has enjoyed an advantage among red-state Dems, despite the perception that he's arguably to Clinton's left, ideologically.

But the angle that stood out for me is that both Nunn and Boren were major players in the drive to launch a Michael Bloomberg presidential campaign.

In fact, both Boren and Nunn, conservative Dems while in Congress, have been so active in the "post-partisan" approach to politics that Nunn even flirted with the idea of being Unity08's presidential candidate. Last August, Nunn told the Atlanta Journal Constitution, "My own thinking is, it may be a time for the country to say, 'Timeout. The two-party system has served us well, historically, but it's not serving us now.'"

And now, with some enthusiasm, he and Bloomberg's other biggest backer are rallying behind Obama. Might Hizzoner be next?