President Trump jumped into campaigns in Michigan, Ohio and Tennessee on Friday, giving his preferred candidates an endorsement that has been pivotal in other races.
In tweets posted five minutes apart and containing some identical language, Mr. Trump endorsed John James in the Republican Senate primary in Michigan and Troy Balderson in a special House election in Ohio, saying each man was “strong on crime and borders, loves our Military, our Vets and our Second Amendment.”
A few hours later, again using the same language, he endorsed Representative David Kustoff of Tennessee against a primary challenger.
It is not clear how significant his endorsement will be for Mr. Balderson, who already won his primary and is now facing a Democrat, Danny O’Connor, on Aug. 7. For Mr. Kustoff — who is facing a primary challenge from George Flinn, a perennial candidate who has lost four previous congressional races but can afford to pour millions of dollars of his own money into his campaigns — it could be more valuable.
But it may ultimately be Mr. James who reaps the most benefit from the president’s support.
Mr. James, a combat veteran and businessman, is in an extremely close Republican primary with Sandy Pensler, also a businessman. Whoever wins will challenge Senator Debbie Stabenow, the Democratic incumbent, in November, and Mr. James and Mr. Pensler have worked hard to tie themselves to the president, knowing how influential his support has been for other candidates in this election cycle.
Mr. James quickly thanked Mr. Trump for his endorsement on Friday and said in a statement, “President Trump endorsed me because he knows that I have the experience, from the battlefield to the boardroom, to secure the borders, defend our Constitution and protect Michigan jobs.”
Mr. Pensler, for his part, said he was “disappointed that President Trump has decided to make an endorsement in this campaign,” and continued to emphasize his Trump-supporting bona fides.
“I have run a campaign strongly in support of the president’s policies of lowering taxes, reducing regulations and protecting our borders,” Mr. Pensler said in a statement, adding, “My support continues for President Trump and his policies, and I believe Michigan Republican voters will see that I have a greater depth and understanding of the issues and will be a stronger voice for our great state in the U.S. Senate.”
The Trump-centered dynamic of the race is not surprising given the pattern seen so far this year: From Alabama and Georgia to South Carolina and Virginia, candidates who received Mr. Trump’s endorsement or were viewed as Trumpian have won, and candidates who criticized Mr. Trump have struggled.
Just this week, in Georgia, Brian Kemp — a hard-line conservative who ran ads promising to “round up” illegal immigrants and suggesting, gun in hand, that any man who wanted to date his daughter should have “a healthy appreciation for the Second Amendment” — won a landslide victory in a Republican runoff that in some ways resembled the Michigan race. He and his opponent, Lt. Gov. Casey Cagle, had both tried mightily to cast themselves as the most Trump-like, and Mr. Trump issued a verdict at the last minute in favor of Mr. Kemp, taking some Republicans by surprise.
In the primary in May, Mr. Cagle led by more than 13 percentage points, but in the runoff, Mr. Kemp won by almost 40 points. And while Mr. Cagle was also hurt by the release of a secret recording in which he said the primary was about “who had the biggest gun, who had the biggest truck and who could be the craziest,” the president’s endorsement of Mr. Kemp may have been an even bigger factor. The Atlanta Journal-Constitution obtained internal polls from Mr. Cagle’s campaign that showed his numbers plummeting immediately after the president’s endorsement of his opponent.