Montana Republican congressional candidate Greg Gianforte allegedly assaulted a reporter at a campaign event in Bozeman on Wednesday evening, one day before voters go to the polls to fill the seat vacated in March by Interior Secretary Ryan Zinke. The reporter, Ben Jacobs of the Guardian, had previously broken a major story about Gianforte’s investments in Russian companies.

Greg Gianforte just body slammed me and broke my glasses — Ben Jacobs (@Bencjacobs) May 24, 2017

Jacobs broke the news of the alleged assault on Twitter. Alexis Levinson, a reporter for BuzzFeed News, immediately confirmed parts of his account in a series of tweets, describing “a loud crash” followed by Jacobs’ feet flying through the air, and not long after, the arrival of Gallatin County sheriff deputies on the scene.

According to audio of the encounter posted by the Guardian, Gianforte’s outburst came after Jacobs asked him about the Congressional Budget Office’s analysis of the GOP health care bill, which Gianforte had previously signaled he was supportive of. “I am sick and tired of you guys!,” Gianforte can be heard shouting. “The last guy who came in here did the same thing. Get the hell out of here!”

In a statement, a Gianforte spokesman blamed Jacobs for the incident, asserting that Jacobs was responsible for “pushing them both to the ground.”

Statement from Gianforte on @bencjacobs: “aggressive behavior from a liberal journalist” pic.twitter.com/yUkQaxg02H — Holly Bailey (@hollybdc) May 25, 2017

You can listen to audio of the incident posted by the Guardian here:

Gianforte has led in public polling against Democrat Rob Quist, a country music star who has the support of Vermont Sen. Bernie Sanders. But the race has tightened in recent weeks, and both parties have invested heavily in advertising. Donald Trump Jr., the president’s son, traveled to the state to round up support for Gianforte, and Vice President Mike Pence recorded a robo-call to help get out the vote. Although the state is reliably Republican in presidential contests, the at-large seat is seen as a possible opportunity for Democrats to chip away at the GOP’s House majority and make a major electoral statement six months after their November catastrophe.

The alleged assault could give Quist a boost, but thanks to the way Montana elections work, it might be a small one. Because of the state’s generous vote-by-mail law, 250,000 people—a large percentage of the voting population—already cast their votes before Wednesday’s news.

Update: Three members of the Fox News crew that was preparing to interview Gianforte when the incident happened have now corroborated Jacobs’ account, and added some new details:

Gianforte grabbed Jacobs by the neck with both hands and slammed him into the ground behind him. Faith, Keith and I watched in disbelief as Gianforte then began punching the man, as he moved on top the reporter and began yelling something to the effect of “I’m sick and tired of this!”

After Jacobs left the room, Fox News’ Alicia Acuna reported, “Gianforte looked at the three of us and repeatedly apologized.”