Former Rep. Pete Hoekstra (R-Mich.) became the instant front-runner in the GOP to challenge Sen. Debbie Stabenow (D-Mich.) when he entered the race on Wednesday. But another serious candidate could join him soon: Clark Durant, who helped create a network of private Christian schools for low-income students in Detroit, is seriously considering a race and will make a decision by the end of July, he told top Michigan Republican official Saul Anuzis on Wednesday.

Hoekstra had initially resisted running, but when it seemed like the GOP couldn't find anyone else to challenge Stabenow he changed his mind. He is and will likely remain the front-runner for the nomination, with high name recognition among the state's conservatives after a second-place finish in the 2010 gubernatorial primary and a strong base of support in western Michigan.

But Durant could shake up the race. He is well-known around the state from his work with the Cornerstone Schools and has a deep donor network he has cultivated for the program, which could make the race competitive. Of the current candidates, only Oakland County Water Resources Commissioner John McCullough is viewed as a credible challenger to Hoekstra.

"Clark is one of the best fundraisers in the state, he's well respected in metro Detroit, and has a great story with the Cornerstone Foundation," said Anuzis.

Hoekstra will be a formidable candidate because he is well-known and well-respected by Republicans in the state, but the primary won't be an "easy ride" for him, according to Anuzis.

Durant has run unsuccessfully for office before, finishing second in a 1990 GOP Senate primary and losing a run for the state's Supreme Court. But Durant's base of support in Detroit's wealthy suburbs could match up favorably against Hoekstra's western Michigan base: If he can unite local Republicans around his candidacy, he could have the money to win the primary.

Republicans are hopeful they can knock off Stabenow, a two-term incumbent who won reelection with 57 percent of the vote in 2006. A poll released Tuesday indicated she could be in trouble: 38 percent of voters approve of the job she's doing while 51 percent disapprove, according to Lansing-based pollster EPIC-MRA. Stabenow remains relatively popular personally, however: 47 percent of voters have a favorable opinion of her, while 35 percent have an unfavorable opinion.

Part of Stabenow's problems stem from the local economic climate: Michigan has one of the highest unemployment rates in the nation and the economic downturn has soured voters on President Obama. He won the state with 57 percent of the vote in 2008, but only 47 percent of voters approved of him in the poll.

Stabenow also faces demographic challenges: Detroit, the state's treasure trove of Democratic votes, has seen its population plummet by 25 percent in the last decade.

This post was updated at 3:40pm to include the EPIC-MRA poll information.