It looks like the idea of Powell as Democratic convention keynote speaker is a nonstarter, according to Karen Tumulty:

A source who familiar with the conversations tells me that Powell informed both John McCain (at a meeting in Arlington a couple of weeks ago) and Barack Obama (at a subsequent one in Powell's Alexandria office) that he does not intend to endorse a candidate--if he does--until after the two parties hold their conventions in late summer. Powell also laid out the considerations that will determine that decision. He told the two that he wants to see who they pick as their running mates, and to get a better sense of the direction that the two candidates are going in the general election season. He also wants to have a clearer idea of where they stand on a number of issues, of which Iraq is only one. [Emphasis added.]

So, that raises the question of who will get the Democratic keynote. In the recent past, the Democrats have reserved the spot for up-and-coming pols: Obama in '04; Harold Ford in 2000; Bayh in '96; even Zell Miller in '92 was, at the time, considered something of a rising Democratic star. I'd imagine Jim Webb would get some consideration if he doesn't wind up as Obama's running mate; Mark Warner would probably get some, too. And then there's Ken Salazar. Any talkbackers have any other ideas?

P.S. And does anyone think there's any way Lieberman won't be the Republican keynoter? 

--Jason Zengerle