WASHINGTON (AP) -- 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.
Romney tweeted his delight - and his determination: "I take great pride in my Michigan roots, and am humbled to have received so much support here these past few weeks. On to the March contests."
The two other candidates, Newt Gingrich and Ron Paul, made little effort in either state, pointing instead to next week's 10-state collection of Super Tuesday primaries and caucuses.
Romney's Arizona triumph came in a race that was scarcely contested, and he pocketed all of the 29 Republican National Convention delegates at stake in the winner-take-all state.
Michigan was as different as could be - a hard-fought and expensive battle in Romney's home state that he could ill afford to lose and Santorum made every effort to win.
Returns from 75 percent of Michigan's precincts showed Romney at 41 percent and Santorum at 37 percent. Paul was winning 12 percent of the vote to 7 percent for Gingrich.
Santorum was already campaigning in Ohio, one of the Super Tuesday states, when the verdict came in from Michigan.
"A month ago they didn't know who we are, but they do now," he told cheering supporters, vowing to stay the conservative course he has set.
In Michigan, 30 delegates were apportioned according to the popular vote. Two were set aside for the winner of each of the state's 14 congressional districts. The remaining two delegates were likely to be divided between the top finishers in the statewide vote.
With his victory in Arizona, Romney had 152 delegates, according to The AP's count,, compared to 72 for Santorum, 32 for Gingrich and 19 for Paul. It takes 1,144 to win the nomination at the Republican National Convention in Tampa next summer.