Actor Sam Waterston praised the personal attributes of "Law and Order" co-star Fred Thompson but warned that if the former Senator enters the Republican presidential field he will be forced to run the "gauntlet" of conservative interest groups to win the nomination. "Everyone is obliged to trim their answers," to please the party's base, said Waterston, a leader of Unity08, a third-party movement... Former Gov. Angus King (I-Maine), another leader of the new group, said the current Republican campaign underscores the negative impact of this sort of base politics, noting that candidates including John McCain and Mitt Romney have had...