FORGET MAGAZINES AND EDITORIAL PAGES. The only endorsements that really matter in the GOP House leadership contest are those from the members themselves, especially the members with clout. Two such Republicans are Jim Sensenbrenner, chairman of the House Judiciary Committee, and Mike Pence, head of the conservative Republican Study Committee (RSC), both of whom endorsed Arizona congressman John Shadegg this week. Shadegg, an erstwhile chief of both the RSC and (more recently) the Republican Policy Committee, remains a dark horse–but he’s gaining steam. “The ‘Big Mo’ is on our side,” says one pro-Shadegg Republican.