Washington and Des Moines - Throughout the roller-coaster Republican presidential contest, one thing hasn't changed: the stubborn refusal of many tea party supporters to warm up to Mitt Romney. The swift rise and abrupt fall of a succession of GOP candidates has been driven in part by the restless search for a Romney alternative by that group of voters, who energized the GOP's big turnaround in 2010. "They don't trust Mitt Romney," said Simon Conway, a Des Moines radio host popular with tea party followers. "Mitt Romney can be tea party one minute, and the next minute introduce 'RomneyCare'" —...