More VP Tea Leaves

What's a game of vice presidential guessing without a big twist at the end? What everyone knows (or is at least very sure of) is that Barack Obama will unveil his running mate by tomorrow when he's scheduled a large rally at the Old State House in Springfield, Illinois. What we don't know is exactly when – or more importantly, who – the selection is to be.

The primary focus remains on Virginia Governor Tim Kaine, Indiana Senator Evan Bayh, Delaware Senator Joe Biden and Kansas Governor Kathleen Sebelius. But a new name has suddenly been thrust into the mix. CBS News has confirmed that Texas Representative Chet Edwards was among those vetted by the Obama campaign and is "a finalist" for the running mate slot.

A rising star for the party in an extremely Republican state, Edwards has long been talked about as running mate material. But he is relatively unknown outside of Texas and political circles and may not mesh in the minds of many voters with the qualifications Obama told Harry Smith this morning he is most looking for. Obama said he's looking for a potential president, saying, "the most important question is is this person prepared to be president?" It would take a massive effort to introduce Edwards as that to the voters.

On the Republican side, the tea leaves also continue to pile up. CBSNews.com chief political consultant Marc Ambinder reports there is "apparently going to be a major political event in Grand Rapids, Michigan on or about 8/31" – that's Saturday, the day after McCain is expected to unveil his running mate. Of course Michigan is the former home of Mitt Romney, whose presence on the ticket could put the state in play this fall. But, as Ambinder points out, as a potential swing state, Michigan would be part of a VP tour with just about any potential candidate. There are hints that McCain will make his first appearance with his running mate in Ohio next Friday.

Meanwhile, Romney has moved back into the top slot on our GOP Vice Presidential Hot Sheet, with Minnesota Governor Tim Pawlenty back in the number two position. Others moving are former Pennsylvania Governor Tom Ridge, Florida Governor Charlie Crist and Connecticut Senator Joe Lieberman.