Speaker Kevin McCarthy’s (R-Calif.) vow to block Rep. Ilhan Omar (D-Minn.) from sitting on the House Foreign Affairs Committee has hit an early snag: he may not have the votes to do it. Omar, one of three Muslims in Congress, has been a controversial figure on Capitol Hill for her sharp criticisms of the Israeli government and its human rights record. Republicans have said she’s crossed a line into antisemitism, and McCarthy’s case for booting her from Foreign Affairs rests on that accusation. But McCarthy has a math problem to solve, one that could prove an early test of his...