HELENA, Mont. (AP) — Montana Secretary of State Corey Stapleton said Saturday he’s leaving the crowded gubernatorial race to become the first Republican to run for the state’s newly open U.S. House seat.

Stapleton’s change of course comes a day after U.S. Rep. Greg Gianforte launched his campaign for governor, which boosted the field of GOP primary candidates to six. Stapleton, 51, told delegates at the Montana Republican Party convention in Helena that there are plenty of good people running for governor, so he will seek to keep Gianforte’s seat in GOP hands.

“I’m from Montana. I can win the big race. You know it. We need to do that. This seat is too important,” Stapleton said.

Gov. Steve Bullock, who can’t run again because of term limits, is competing for the Democratic presidential nomination. State Rep. Casey Schreiner and former legislator Reilly Neill are the two Democrats who have announced their candidacies for governor so far.

Stapleton was the first prominent Republican to announce his run for governor back in January, before Attorney General Tim Fox, state Sen. Al Olszewski and Gianforte joined the race.

Stapleton is now staking out early ground in what’s likely to be a competitive primary for the Republican nomination for U.S. House, with State Auditor Matt Rosendale and former District Judge Russ Fagg also considering runs.