BISMARCK, N.D. (AP) — State Sen. Kelly Armstrong easily won Tuesday's Republican primary for North Dakota's U.S. House seat being vacated by Rep. Kevin Cramer.

As Cramer seeks to move into the U.S. Senate — he won his own primary against a little-known opponent — Armstrong is hoping to keep the GOP's grip on a seat the party has held since 2010.

Armstrong breezed past former Marine and first-time candidate Tiffany Abentroth and Paul Schaffner, a former North Dakota State football player. Armstrong's closest opponent was actually state Sen. Tom Campbell, who dropped out of the race weeks ago.

Campbell spent hundreds of thousands of dollars on a Senate bid before Cramer squeezed him out of that race and into the House race.

Armstrong, 41, left his post as the state Republican Party chairman to run after Cramer announced a bid for the Senate. He'll face Mac Schneider, a former two-term state senator who ran unopposed for the Democratic nomination.

Armstrong, an attorney, has strong ties to North Dakota's oil industry. His father, Mike, is a longtime oil driller who has been a competitor, colleague and bird-hunting buddy for decades with billionaire Harold Hamm, considered the godfather of North Dakota's oil industry.

Schneider, 39, is a businessman and attorney who was defeated for re-election in the Senate in 2016. He served as minority leader in two legislative sessions.

In a debate in April, Armstrong and Schneider largely agreed on fewer federal regulations and giving more control to local governments. Armstrong supports President Donald Trump's tax cuts and trade policies, while Schneider doesn't.

Armstrong has a significant money edge, with almost $400,000 in the bank compared to Schneider's $191,000, according to federal reports.