Failed presidential candidate John Kerry is considering filing a libel suit against the leader of the group Swift Boat Veterans for Truth, John O'Neill, whose book "Unfit for Command" is credited with capsizing Kerry's Vietnam War-based campaign. "I don't know if they will actually go forward," a member of Kerry's inner circle told New York Post's Page Six column, edited by Richard Johnson. "But consideration is serious. If Kerry plans on running again in 2008 — and I'm hearing he will — it would make sense that he'd file the suit." Co-written by Jerry Corsi, "Unfit" sold more than 800,000...