Rep. Rob Simmons has picked up some powerful support in his campaign to oust Democratic Connecticut Senator Chris Dodd. Jonathan Bush (the brother of President No. 41 and uncle of 43) is tapping his extensive Rolodex to spread the word about tomorrow’s fund-raiser at the swank River Club on East 52nd Street. Henry and Nancy Kissinger, who weekend in Lakeville, Conn., are chairing the $1,000-a-head soiree. In a note to friends, “Jon” Bush (the father of TV star Billy Bush) says, “Come and meet Rob Simmons. He’s a true American hero!” Jon, who lives in Easton, is a son of Prescott Bush, who once held Dodd’s seat.