Hotline heightens the speculation with this tidbit:

It’s worth noting that David Plouffe, Barack Obama’s campaign manager, is traveling with the candidate today (which I understand happened only a handful of times), reports NBC/NJ’s Mike Memoli. He’s joining Obama advisers David Axelrod and Robert Gibbs for the DC trip.

Caroline Kennedy is also in Washington for a DNC victory fund event. And Eric Holder, the other VP search team leader, is based in DC.

The convergence of all the senior staff here with that search committee only further signals that the process is at a critical stage. The campaign, of course, is not commenting on it.