Republican Greg Gianforte overcame an election eve assault charge filed against him that sparked national attention, defeating Democrat Rob Quist in the race for Montanas open U.S. House seat Thursday.

Gianforte received 50.2 percent to Quists 44.1 percent. Libertarian Mark Wicks picked up 5.7 percent of the vote.

The result is a major disappointment for progressive activists who poured money into the campaign to help Quist, a banjo-playing songwriter and political newcomer, in a bid to notch a symbolically important win against President Donald Trump.

Your voices were definitely heard in this election, Quist told supporters after the results were final. I know we came up short, but the energy in the state and the grassroots movement in the state goes on.

The defeat is especially demoralizing for Democrats in light of the misdemeanor assault charge against Gianforte, a multimillionaire tech entrepreneur and social conservative, for allegedly body slamming Ben Jacobs of The Guardian on Wednesday while the reporter was asking about the GOP health care bill . Gianfortes campaign blamed Jacobs, casting him as a liberal reporter who acted aggressively toward the Republican as he was about to be interviewed by a TV crew. But Alicia Acuna, the Fox News reporter who was slated to interview Gianforte, corroborated Jacobs version of events, and the incident spurred widespread condemnation of the Republican.

Last night I made a mistake, Gianforte said in his victory speech Thursday night. I should not have responded in the way that I did, and for that Im sorry.

The Democratic Congressional Campaign Committee and the liberal group MoveOn.org had blasted Gianforte with a last-minute ad campaign highlighting the incident as evidence he was unfit to serve and had no business being in Congress.

House Speaker Paul Ryan (R-Wis.) urged Gianforte to apologize earlier Thursday and called his behavior wrong. And three Montana newspapers withdrew their endorsement of him.

The Missoulian newspaper said there is no doubt that Gianforte committed an act of terrible judgment that, if it doesnt land him in jail, also shouldnt land him in the U.S. House of Representatives.

A factor likely benefiting Gianforte was that before news broke of Wednesdays altercation, more than two-thirds of those who voted in the election had already cast early ballots, according to state election officials. Still, Quists loss will inevitably fuel criticism that the national Democratic Party got involved in the race too late.

Even before Thursdays results were known, Jeff Hauser, a veteran progressive political strategist at the Center for Economic and Policy Researchs Revolving Door Project, had told HuffPost that the national Democrats who provided financial assistance after mail-in voting had already begun will have to question anew their initial reluctance to engage in the race in March and early April.

Early funding might have ensured more consistent tracking on Gianforte, Hauser added, referring to the attack on the reporter. It almost seems like you never know when Gianforte might commit a crime under a modicum of scrutiny.

Under almost any circumstances, a Democratic win would have been an upset. Even as Quists standing improved in the campaigns final weeks, none of the polls released in advance of the race showed him ahead of Gianforte.

Montanas at-large U.S. House seat opened up in December when Trump tapped Ryan Zinke as his interior secretary. Republican Zinke had cruised to re-election in November by nearly 16 percentage points . Trump carried the state over Democratic rival Hillary Clinton by 20 points.

Democratic presidential candidates have triumphed in the state just twice since 1952, most recently when Bill Clinton won it in 1992.

Still, in a state with a sizable segment of independents, Democrats at times have held their own in down-ballot races. One of them is current Gov. Steve Bullock, who won re-election in 2016 when he defeated Gianforte by 4 percentage points.

Quist, 69, a native-born ranchers son from the Flathead Valley and founder of the popular Mission Mountain Wood Band, had the profile to repeat Bullocks success. But Montanas GOP leanings proved insurmountable in a traditionally low-turnout special election.

When this race started, I thought Quist had a 1-in-5 chance, Jorge Quintana, a Democratic National Committee member from Montana, told HuffPost. I dont think any Democrat has been disappointed with the way Quist has behaved in this campaign. He has raised a ton of money. And he has hit the state hard Montanans expect that.