(DAYTON, OHIO) -- John McCain is expected to announce his running mate today at the Ervin J. Nutter arena here on the campus of Wright State, but so far he has kept quiet about who that choice is. Mitt Romney is the top choice of Republican delegates for the job, with 38 percent hoping McCain picks him for VP, according to a CBS News poll, but CBS News has learned that Romney will not be in Dayton this morning, which would appear to cross him off the VP list.
Even though he only garnered 4 percent of the delegates polled, Tim Pawlenty's stock has risen in recent weeks, and the Minnesota governor has cleared his schedule for the next couple of days (as have other top VP choices). But Pawlenty told the CBS affiliate in Minneapolis he would not be joining McCain in Dayton today. "I'm not going to be there," Pawlenty said. "I plan to be at the state fair. You can draw your conclusion from that."
So who's left? Alaska governor Sarah Palin has been mentioned, although she is not well-known outside Alaska and has little national experience. McCain's "favorite Democrat" Joe Lieberman has also been mentioned, as has former Homeland Security chief Tom Ridge, but both of them support abortion rights, which would be a hard sell to conservatives.
Former eBay CEO Meg Whitman and former HP CEO Carly Fiorina are also seen as dark horses for the job, although neither of them have political experience.
The big announcement comes at noon ET today.