Marine Corps Veteran Mike Gallagher won the Republican primary in Wisconsin's open 8th District Tuesday night.
He carried 73 percent of the vote in the three-way primary, with just 29 percent of precincts reporting, according to the Associated Press.
GOP Rep. Reid Ribble, an outspoken critic of Donald Trump and the second member of the House Freedom Caucus to resign from the group, is retiring at the end of this term.
Ribble backed Gallagher, who has said he will support the GOP presidential nominee.
After working for the Senate Foreign Relations Committee, Gallagher served as national security adviser to Gov. Scott Walker's presidential campaign.
Gallagher defeated state Sen. Frank Lasee in the primary and will face off in November against Outagamie County Executive Tom Nelson, who didn't have a primary.
Democrats have made this seat a top-target. The Democratic Congressional Campaign Committee and House Majority PAC have reserved nearly $1 million combined in airtime for this district for the fall.
Shortly after winning his own primary in Wisconsin's 1st District, Speaker Paul D. Ryan endorsed Gallagher and said he'll campaign with him in the 8th District this fall.