<p>Fifteen years after John McCain rolled out his Straight Talk Express campaign bus, Jeb Bush unveiled his own tricked out version, hoping to revive his flagging fortunes with a McCain-like dose of frankness and free-wheeling banter with the campaign press corps. </p><p>The unvarnished chats with small groups of reporters accomplished one thing: They revealed a humbled, good-humored candidate well aware of his difficult predicament.