Oklahoma Representative Kevin Hern (R) formally announced his campaign for the U.S. Senate on Wednesday, becoming the first Republican to enter the primary race to replace Sen. Markwayne Mullin (R), who was recently tapped by President Donald Trump to lead the Department of Homeland Security.

Hern, a businessman and McDonald’s franchise owner who was first elected to Congress in 2018, currently represents Oklahoma’s First Congressional District, which includes the Tulsa area. In a social media video announcing his candidacy, Hern highlighted his upbringing on an Air Force base, business experience, and congressional service as preparation for higher office.

“I’m ready to fight for Oklahoma in the Senate,” Hern said. He also framed his campaign as a defense of President Trump’s policies, stating he would be “a loyal ally” in the Senate. Hern criticized both Democrats and “RINO Republicans” who, he said, oppose Trump’s America-first agenda.

Key issues outlined in Hern’s announcement include securing the southern border, deporting immigrants, supporting law enforcement, and promoting economic affordability. He concluded the video by calling himself “America first and Oklahoma proud.”

The Republican primary is scheduled for June 16, with candidates required to file from April 1 through April 3. Early reporting indicated Hern is likely to enter the race with a significant financial advantage, including the ability to contribute $5 million of personal funds, half of which is already in his campaign account. Political strategists have cited his wealth, name recognition, and alignment with the Trump base as factors making him a strong frontrunner.

Other potential Republican candidates are considering entering the race. Rep. Stephanie Bice (R-Okla.) recently suggested she is weighing a campaign but has not yet declared. Analysts say Hern’s early announcement and financial resources could discourage challengers.

Mullin’s departure from the Senate triggers a temporary appointment process. Oklahoma Gov. Kevin Stitt (R) will have 30 days to appoint a Republican to fill the seat until the November general election. The appointee must pledge not to run for a full term, leaving the election open to the winner of the primary contest.

Hern’s Senate bid will also have downstream effects in the First Congressional District, creating a competitive Republican primary for his House seat in the 2026 election cycle. The campaign marks a critical moment for Oklahoma Republicans as they aim to maintain control of both seats in the U.S. Congress while supporting Trump-aligned candidates.