The liberal challenge to Sen. Joe Lieberman (D-Conn.) escalated Friday when the political arm of MoveOn.org, an influential online advocacy group, endorsed the political newcomer opposing his bid for renomination. Gaining the support of MoveOn's political action committee was Ned Lamont, a businessman who wants to unseat Lieberman largely because of the veteran lawmaker's staunch support for the war in Iraq. The group announced its backing after polling MoveOn's members in Connecticut. MoveOn has emerged as a leading voice for left-leaning activists, and the endorsement marks the first time that its PAC has sought to unseat an incumbent Democratic senator....