With 29 percent of precincts reporting, The Associated Press declared James the winner over 61-year-old financier Sandy Pensler, with 57 percent of the vote.

The race between James and Pensler had been in a dead heat in the weeks before the primary. A poll conducted late last month for the Detroit Free Press showed it as a toss-up, with James taking 39 percent support among likely GOP primary voters and Pensler taking 38 percent.

Pensler also had more money than James leading up to primary day. He loaned $5 million of his own fortune to his campaign as he kicked off his Senate bid earlier this year, and reported having about $1.25 million cash on hand in his most recent Federal Election Commission filing.

But James’s credentials have made him a darling of Republican politics. The 37-year-old graduated from West Point in 2004, before serving eight years in the Army, and he currently runs James Group International, which provides logistics solutions to Fortune 500 companies.

But Trump’s endorsement on July 27 boosted James in a race in which both men competed over their support for the president. Pensler acknowledged that he was “disappointed” that Trump chose James over him in the race but vowed to “continue fighting through.”

Trump has become a kingmaker for some Republican candidates. In Georgia’s GOP gubernatorial runoff last month, for example, Secretary of State Brian Kemp trounced Lt. Gov. Casey Cagle by a nearly 40-point margin after receiving Trump’s support.

But how Trump-endorsed candidates will fare in the fall remains uncertain.

While he may have vanquished Pensler in the GOP primary on Tuesday, James is likely to face a difficult bid against Stabenow in November in a state that Trump won by less than half a point in 2016.

Stabenow, a three-term senator, did not face a primary challenger, and will go into the general election with a huge cash advantage over James.

At the end of June, Stabenow reported having about $9.6 million cash on hand, according to her most recent Federal Election Commission filing. James, on the other hand, reported having about $868,000 cash on hand in his pre-primary filing on July 18.

An NBC News/Marist poll released late last month also showed Stabenow with a wide lead in a potential matchup against James – 55-37 percent.