JACKSON, Miss. (AP) - Sen. Thad Cochran, R-Miss., has endorsed Mitt Romney's bid for the White House and says he would welcome an opportunity to help the Republican "implement his conservative vision'' if elected. "It is an honor to join Governor Romney and his campaign for our nation's highest office,'' Cochran said in a statement released by the Romney campaign and confirmed by Cochran's office. "At this moment our nation faces unprecedented challenges, and Governor Romney has the experience, vision and values needed to strengthen our country for future generations,'' Cochran said in the statement. "Governor Romney is a man...