Romney sweeps to double Republican primary victory

WASHINGTON — Mitt Rom­ney scored a hard-won, home state tri­umph in Michi­gan and pow­ered to vic­tory in Ari­zona Tues­day night, gain­ing a two-state pri­mary sweep over Rick San­to­rum and pre­cious momen­tum in the most tur­bu­lent Repub­li­can pres­i­den­tial race in a generation.