Democrat Harley Rouda will face California Rep. Dana Rohrabacher in November after a long primary ballot count.

Rouda, a real estate developer, edged out his Democratic opponent Hans Keirstead, who conceded the second-place finish in the June 5 primary on Sunday after a weeks-long ballot count.

Keirstead pledged his support for Rouda in a Facebook post Sunday, which highlighted the importance of science in public policy. Science had been a major campaign theme for Keirstead, a stem cell researcher.

“I know the Rouda campaign values the importance of science and facts in public policy, and they will give voice to that message,” Keirstead wrote.

Rouda announced Keirstead’s concession in a tweet Sunday evening.

I just got off the phone with @drhanskeirstead. We congratulated each other on a hard fought primary and he pledged his full support to our campaign to #flipthe48th and defeat @RepRohrabacher. #ThankYouHans

— Harley Rouda (@HarleyRouda) June 25, 2018

Rouda now faces Rohrabacher, the 15-term incumbent Republican, in the fight to represent the 48th District of California. Rohrabacher led the primary field with 30 percent of the vote.

Democrats are hoping to flip the seat in November as part of their mission to take the House, and Rohrabacher is considered vulnerable. The race for the seat is rated Tilt Republican by Inside Elections with Nathan L. Gonzalez.

“In the days and weeks ahead, I will continue fighting every day to hold Dana Rohrabacher accountable for his reckless, backward agenda that spans from Orange County all the way to Washington,” Rouda said in a press release Monday.

Rohrabacher defeated his Democratic opponent in 2016 by 16 points, while Hillary Clinton narrowly edged out President Donald Trump in the district.

In California, candidates of all parties run in a single primary race. The top two vote recipients in the primary face each other in the general election in November.

Rouda led Keirstead by only 126 votes at last count, the Los Angeles Times reported.

Democrats had concerns that Rouda, Keirstead and six other Democrats on the ballot could split the vote and allow another Republican candidate to make the runoff against Rohrabacher.  The Democratic Congressional Campaign Committee ran hundreds of thousands of dollars in advertisements supporting Rouda in the end stages of the campaign.