Voters in three more states have decided which Republican candidate they want to see in the race for the White House next fall.

The results were a surprise to many people. Former U.S. Senator Rick Santorum of Pennsylvania came out on top in all three states—Colorado, Minnesota, and Missouri. Santorum’s strong performance has shown that the race may be more wide-open than people had thought.

Many expected former Massachusetts Governor Mitt Romney—who is widely considered to be the Republican front-runner, or leading candidate—to win Colorado and probably Minnesota. He had won several important primaries in January. Also, he won both of those states when he ran for the Republican presidential nomination in 2008.

But Santorum won handily, with 45 percent of the vote in Minnesota’s caucuses and 40 percent of the vote in Colorado’s. Romney came in third in Minnesota. Texas Congressman Ron Paul, who campaigned heavily in the state, came in second. Romney came in second in Colorado.

Santorum’s victory sweep also included Missouri, which held a primary on Tuesday. (The state will officially choose its candidate, and award its delegates, in caucuses next month.)

Going into Tuesday’s contests, former Speaker of the House Newt Gingrich was considered to be Romney’s main rival. Gingrich, who did not campaign heavily in Colorado or Minnesota, took roughly 10 percent of the vote in those states. He wasn’t on the ballot in Missouri.

The results of the primaries and caucuses determine how delegates from each state will vote at the Republican convention in August. That’s where the Republican Party will formally nominate, or name, the candidate who will compete against President Barack Obama, a Democrat, in November.

But many contests still need to take place before that. In Maine, a weeklong series of caucuses will end this Saturday. Several more states will vote throughout February. Then comes Super Tuesday on March 6. That’s when voters in 10 more states go to the polls. More primaries and caucuses are held on that day than on any other.

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