JEFFERSON CITY, Mo. — Michigan Republicans selected former Rep. Pete Hoekstra to take on Democratic Sen. Debbie Stabenow in November, while three GOP contenders were locked in a tight race Tuesday to oppose Democratic Sen. Claire McCaskill in Missouri.

Also in Michigan, Democratic Rep. John Conyers staved off a primary challenge to advance to November’s election, when he will be strongly favored to win a 25th consecutive term in Congress.

In the Missouri contest, U.S. Rep. Todd Akin led ex-state treasurer Sarah Steelman and businessman John Brunner with about half the vote reported. The winner and McCaskill will compete in what will be one of the most closely watched Senate races of 2012.

The GOP must net four seats from Democrats to gain control of the Senate, and Republicans saw McCaskill as among this year’s top targets.

In Missouri, all three Senate hopefuls have lambasted McCaskill for what they say are her close ties to President Obama. The race took on a different dynamic in recent days as Sarah Palin and Mike Huckabee – two of the GOP’s most prominent faces – lent their backing to candidates.

Palin, in particular, has been dogged in her support of Steelman. The 2008 GOP vice presidential nominee has appeared in television and radio ads and campaigned with Steelman.

Akin, who drew Huckabee’s backing, has a strong conservative voting record. But both Steelman and Brunner have sought to use that experience against him, portraying themselves as outsiders.