COLUMBUS, Ohio (AP) — Former President Donald Trump issued a last-minute endorsement in a highly sought northwest Ohio congressional district Monday, backing state Rep. Derek Merrin over a rival Republican whom Trump’s closest ally in the state has described as “a rock-solid conservative.”

Trump’s decision came about 18 hours before polls were set to open on Ohio’s primary election — and less than 48 hours after Trump campaigned in the state on behalf of Cleveland businessman Bernie Moreno, his pick for U.S. Senate.

“Derek Merrin is an incredible America First Patriot who is running for Congress in Ohio’s 9th District against a RINO, Craig Riedel, who is no friend of MAGA,” Trump wrote on his Truth Social platform. “As your next Congressman, Derek will fight hard to Secure our Border, Stop Inflation, Support our Military / Vets, and Protect our always under siege Second Amendment.”

House Speaker Mike Johnson, R-La., tapped Merrin, 38, as his pick to take on Democratic incumbent Marcy Kaptur, 77, the longest-serving woman in Congress, this fall. Kaptur is viewed as among the most vulnerable Democrats in the nation.

Merrin drew statewide attention for leading an intraparty rebellion in the Ohio House last year after a bitter fight over the speakership.

Johnson recruited Merrin after audio surfaced of Riedel criticizing Trump, which raised concerns about his electability in a state that’s twice supported Trump’s presidential bids by strong margins. But that was months ago, back in December, begging the question of why Trump didn’t weigh in earlier.

Notably, Riedel’s campaign recently began airing a searing Merrin attack ad — blasting the legislator as “a top henchman” to then-Ohio House Speaker Larry Householder. Householder was convicted last year in the largest bribery scheme in state history and sentenced in June to 20 years in prison. The ad suggests “speculation swirls Merrin could be charged next.”

In backing Merrin, Trump parted ways with his best known Ohio ally: U.S. Rep. Jim Jordan. Jordan originally endorsed Riedel and stuck by him even after the remarks involving Trump came to light.

Jordan said, “Craig Riedel is a rock-solid conservative who understands that parents, not the government, know what is best for their children. He will fight to cut spending, lower taxes, uphold the Second Amendment, and protect traditional family values.”

Trump’s 11th-hour decision to get involved is merely the latest twist in what has been a roller coaster of a primary marked by swift entries and exits, candidate gaffes and bouncing endorsements. At one point, Johnson, Jordan and the state’s Republican senator, JD Vance, were aligned with three different candidates.

Vance had backed J.R. Majewski, the party’s 2022 nominee, before he suddenly withdrew from the race earlier this month after facing criticism for remarks he made during a podcast denigrating Special Olympics athletes.