Early jockeying has begun in the race for chairman of the conservative Republican Study Committee — the largest caucus on Capitol Hill, and one that has seen its influence grow with Donald Trump in the White House. At least five House Republicans told The Hill they are weighing bids to replace the group's chairman, Rep. Mark Walker (N.C.). Known informally as the RSC, the caucus imposes a two-year term limit on its chairman, giving more members a chance to lead. So far, the possible contenders are: four-term Rep. Vicky Hartzler (Mo.); three-term Rep. Roger Williams (Texas); two-term Rep. Barry Loudermilk...