According to insiders in the McCain campaign:

Insiders close to Sen. John McCain’s presidential campaign have put out the word that there is absolutely no chance that his last remaining major opponent for the Republican presidential nomination, former Arkansas Gov. Mike Huckabee, will become McCain’s vice presidential running mate. McCain personally likes Huckabee, and McCain’s campaign has not wanted to antagonize Huckabee’s evangelical supporters, whose backing will be needed in the general election. But McCain’s close advisers reject a place on the ticket for Huckabee, who is unacceptable to economic conservatives.