Rep. Kevin Hern has won the Republican Senate primary in Oklahoma, NBC News projects, paving the way for him to win the open seat in the general election.

The seat was previously represented by Department of Homeland Security Secretary Markwayne Mullin, who resigned from the Senate in March to replace former Secretary Kristi Noem in the Cabinet.

Hern, who was first elected to the House in 2018, decided to leave that chamber to attempt the leap to the Senate. Hern currently represents Oklahoma’s 1st Congressional District, which covers most of Tulsa, and serves on the powerful House Ways and Means Committee.

Before his time in Congress, he was a McDonald’s restaurant franchisee. Sen. Alan Armstrong was appointed to fill the Senate seat for the remainder of Mullin’s term, before the fall election.

President Donald Trump endorsed Hern in a Truth Social post in March, in which Trump described Oklahoma’s GOP candidate as “a Great Patriot” and a “true friend of MAGA,” adding that Hern “is doing a tremendous job advancing our AMERICA FIRST Agenda.”

Hern has been a fierce proponent of Trump’s MAGA movement, boasting about the president’s successes on social media.

“The numbers don’t lie: employment is up, wages are up, and hardworking families are succeeding! When we put America First, America Wins!” Hern wrote in a post on X earlier this month.

Oklahoma is a solidly red state and gave Trump a 34-point victory in 2024. Mullin was initially elected in 2022 to finish the remainder of then-Sen. Jim Inhofe’s term, after Inhofe decided to resign.