Sources have exclusively told CBS News Chief Washington Correspondant Bob Schieffer that influential Republicans-some of them inside the Bush White House-are now urging the President to work behind the scenes to get Trent Lott to step down as Majority Leader of the United States Senate.However some Republicans have risen to Lott's defense.Senator Arlen Specter , (R-PA) said Lott's comments should be accepted as an 'inadverdent slip and his apolgy should end the discussion.''I know Trent Lott very well from working with him in the Senate for the past 14 years and can vouch for the fact that he is no...