Likely Democratic nominee Barack Obama has begun a top-secret search for a running mate, fresh signs that the general election campaign is well under way and the primary race against Hillary Rodham Clinton is basically over.
Obama has asked former Fannie Mae CEO Jim Johnson to begin vetting potential vice presidential picks, Democratic officials said Thursday. Johnson did the same job for Democratic nominees John Kerry in 2004 and Walter Mondale in 1984.
Obama refused to acknowledge Johnson's role when The Associated Press asked the Illinois senator about it in the Capitol Thursday.

"I haven't hired him. He's not on retainer. I'm not paying him any money. He is a friend of mine. I know him," Obama said. "I am not commenting on vice presidential matters because I have not won this nomination."

The Democratic officials spoke on a condition of anonymity about a process that the campaign wants to keep quiet.

Vice presidential searches are usually closely held secrets, but Obama campaign officials say the effort is being handled by a particularly tight circle of advisers.
The campaign did not want to discuss the effort because they are still engaged in a fading primary campaign against Hillary Rodham Clinton, with three primaries left in Puerto Rico, South Dakota and Montana. The voting ends June 3. Obama has repeatedly declined to discuss possible running mates while the primary is ongoing.