White House hopeful Barack Obama is close to picking a running mate, with Timothy Kain, the one-term governor of the swing state of Virginia, a prime contender, reports said.Kaine, 50, has told close associates that he has had “very serious” conversations with the Democratic senator about running as his vice presidential nominee, the Washington Post reported on Tuesday.The Obama campaign has been combing through Kaine’s background as part of an in-depth vetting, but is also taking a serious look at senators Evan Bayh of Indiana and Joseph Biden of Delaware, the newspaper said.Both Kaine and Obama were in Washington yesterday but the Virginia governor denied they had any “secret meetings” planned.Asked if he was being vetted, Kaine told Washington radio station WTOP: “I have been on board with the campaign since February of ‘07 but don’t talk about my conversations with the campaign.“It’s flattering to be mentioned. My mom loves it. But that’s or the campaign to decide. and however they decide, they’re going to make a very good decision as Senator Obama chooses his running mate,” he said.One politician not considered as a leading runner for the VP slot is Senator Hillary Clinton, Obama’s defeated rival for the Democratic nomination, both he Post and New York Times reported.Betting on the running mate stakes is intensifying in the run-upto the Democratic convention in late August.