Obama has decided on V.P.

USA Today is reporting this afternoon that Barack Obama has decided on his running mate, but wouldn't say whether he's informed his choice or when he'll tell the world.

"I won't comment on anything else until I introduce our running mate to the world," he told the newspaper in Chester, Va.. "That's all you're going to get out of me."

According to the USA Today report: "Obama said it was a difficult decision. 'We had some great choices.' Obama said he wanted somebody who is 'prepared to be president' and who will be 'a partner with me in strengthening this economy for the middle class and working families.'

He said he was looking for not just a partner but a sparring partner. 'I want somebody who's independent, somebody who can push against my preconceived notions and challenge me so we have got a robust debate in the White House.' "

The other veep buzz is that Obama and his staff met this morning with Virginia Governor Tim Kaine and his staff. Kaine is thought to be high on Obama's short list.

UPDATE: But later, Kaine told reporters that he and his family plan to go to Denver on Friday for the convention. Obama and his running mate are expected to appear together in Springfield, Ill., on Saturday.

And ABC News noted that Kaine seemed to talk about his vice presidential prospects in the past tense. I've always thought it seemed a bit unlikely but I'm not going to tell you it hadn't been fun," he said. "I'm going to let the campaign take from here. They're going to reveal what they want to reveal when they want to reveal it. "It's been nice to be mentioned but I'm going to let them do the heavy lifting at this point."