By David Nather, CQ Staff

It might be the best-attended ambassador nominations hearing ever.

On Tuesday morning, Barack Obama , D-Ill., is scheduled to chair a Senate Foreign Relations Committee hearing where — among other things — senators are set to approve nominations for ambassadors to Finland, Slovenia, Cyprus and Bulgaria.

He’s not flying in just for that, of course. Obama, along with his presidential rivals — Sens. Hillary Rodham Clinton , D-N.Y., and John McCain , R-Ariz. — will be on the Hill for back-to-back hearings in which Gen. David H. Petraeus and Ambassador Ryan Crocker will testify about the Iraq War.

But while McCain and Clinton are listening to the two at an Armed Services Committee hearing in the morning, Obama won’t get his chance until they testify before Foreign Relations in the afternoon. So as the Armed Services hearing goes on three floors below him in the Dirksen building, Obama will kill time with a nominations hearing.

Why him? At first glance, it might look like a reaction to Clinton’s campaign jabs. She’s been hounding him over his failure to hold any hearings of the European Affairs Subcommittee he chairs.

Officially, though, it’s because the nominations hearings are grouped by areas of the world, and they’re always run by the panel chairman who deals with the relevant part of the world. In this case, all the nominations Tuesday morning relate to European countries, which are Obama’s specialty, according to Elizabeth Alexander, a spokeswoman for Foreign Relations Chairman Joseph R. Biden Jr. of Delaware.

Obama has chaired two nominations hearings before, but he hasn’t done one since June. Lucky for him, there just happen to be some nominations waiting on one of those rare days when he’ll be in town.