GOP presidential hopeful Ron Paul has been excluded from an upcoming political forum in Iowa on the grounds that he is not a "credible” candidate. The event, sponsored by Iowans for Tax Relief and the Iowa Christian Alliance, is set for June 30 in Des Moines. GOP candidates who will speak at the forum include Mitt Romney, Sam Brownback, Duncan Hunter, Mike Huckabee, Tommy Thompson and Tom Tancredo. But Paul, a Texas congressman, was left out because the invitation went only to those candidates who are "credible,” said Ed Failor Jr., vice president of Iowans for Tax Relief. "To plan...