Republican Rep. Kevin Hern has defeated Democrat N’Kiyla Jasmine Thomas to win Oklahoma’s U.S. Senate race, securing the seat that became vacant after former Sen. Markwayne Mullin left Congress to join President Donald Trump’s administration as secretary of Homeland Security.

Hern, who represents Oklahoma’s 1st Congressional District, entered the general election after winning the Republican primary with nearly 70% of the vote. His campaign received support from President Trump, who backed Hern during the race and appeared at a Republican rally in Oklahoma in early October. Hern will now leave the House after serving in Congress since 2018 and take on a new role representing Oklahoma in the upper chamber.

The Senate seat opened in March when Mullin resigned to become Trump’s secretary of Homeland Security. Oklahoma Gov. Kevin Stitt appointed Republican businessman Alan Armstrong to serve temporarily until voters selected a successor. Armstrong’s appointment was intended to cover the vacancy, but the November election determined who would hold the seat for the next full Senate term.

The timing of the transition became a point of discussion during the campaign. Oklahoma Attorney General Gentner Drummond issued an opinion in late October concluding that the election winner could take office once the November results were certified, rather than waiting until January 3, when the current Senate term was scheduled to end. The opinion also established that Armstrong’s appointment would end when the newly elected senator became eligible to assume the position.

Hern built his career in business before entering public office. He previously owned and operated McDonald’s franchises in the Tulsa area, eventually expanding his holdings to 18 restaurants. He was elected to represent Oklahoma’s 1st Congressional District in 2018 and became a prominent conservative voice in the House. Hern also served as chairman of the Republican Study Committee, a major conservative caucus focused on advancing limited-government and fiscal conservative policies.

During his time in Congress, Hern supported Republican efforts on tax policy, economic growth, border security and reducing federal spending. His business background became a central part of his political identity, with his campaign presenting his experience as an entrepreneur as an asset in addressing economic concerns facing Oklahoma families and businesses.

Thomas, a nurse, military spouse and mother from Oklahoma, won the Democratic nomination after defeating Jim Priest in the August runoff with more than 61% of the vote. She campaigned on expanding access to healthcare, supporting rural hospitals and addressing the financial pressures facing working families. Her support for Medicare for All placed her to the left of Hern on one of the central policy questions in the race.

The contest also included Libertarian Sevier White and independent candidates Ron Meinhardt and Curtis Stinnett. However, the race largely centered on the choice between Hern’s conservative congressional record and Thomas’ progressive healthcare and economic proposals.

Hern’s victory gives Republicans another senator from Oklahoma and moves a longtime member of the House into a position with a direct role in shaping federal legislation, confirming judicial appointments and overseeing the Trump administration. He will represent Oklahoma for the remainder of the current term and the new six-year term following certification of the election results.