Donald Trump Jr. campaigning in Montana for GOP candidate Gianforte (pictured, right) who was charged last night with assaulting a reporter. | Bobby Caina Calvan/AP

BOZEMAN, Mont. (AP) — The Republican candidate for Montana’s sole congressional seat was charged with misdemeanor assault Wednesday night after witnesses told police Greg Gianforte grabbed a reporter by the neck and slammed him to the ground the night before polls close in the nationally-watched election.

A Montana sherriff filed assault charges against Gianforte, the Republican candidate for the state’s only Congressional district for assaulting a reporter. The attack took place here on the eve of a hotly contested special election for that seat.

Gallatin County Sheriff Brian Gootkin made the announcement late Wednesday in a statement posted to the county web site. Gianforte would face a maximum $500 fine or 6 months in jail if convicted. The statement added that the reporter’s injuries did not meet the legal definition of felony assault.

A Fox News crew watched in astonishment as, after Jacobs pressed him on the GOP health care bill, “Gianforte grabbed Jacobs by the neck with both hands and slammed him into the ground behind him,” Fox News reporter Alicia Acuna wrote in an article . She added that Gianforte then began to punch Jacobs.

In an audio recording posted by the Guardian, the reporter asks the congressional candidate about the GOP’s health care bill, which was just evaluated hours earlier by the Congressional Budget Office.

“We’ll talk to you about that later,” Gianforte says on the recording, referring Jacobs to a spokesman.

When Jacobs says that there won’t be time, Gianforte says “Just–” and there is a crashing sound. Gianforte yells, “The last guy who came here did the same thing,” and a shaken-sounded Jacobs tells the candidate he just body-slammed him.

“Get the hell out of here,” Gianforte says.

The Sheriff’s office said that Gianforte was cited Wednesday night. He has until June 7 to appear in court on the charge.

Federal records show that the sheriff donated $250 to Gianforte’s congressional campaign in March. In his statement, Gootkin confirmed the donation but said, “This contribution has nothing to do with our investigation, which is now complete.”

The incident is a last-minute curveball in Thursday’s race, which was partly seen as a referendum on Donald Trump’s presidency. The majority of voters were expected to have already cast ballots through early voting, and it was unclear how much of an effect it may have.

Gianforte and Democrat Rob Quist, who declined to comment, are seeking to fill the state’s seat in the U.S. House left vacant when Ryan Zinke resigned to join Trump’s Cabinet as secretary of the Interior Department.

Gianforte, a wealthy businessman, lost a race against Montana’s Democratic governor in November while Trump won the state by 20 points. In the congressional race, Gianforte has tried to tie himself to the president and has been boosted by visits from Vice President Mike Pence and Donald Trump, Jr. Democrats were hoping an upset would send a message to the GOP that Trump’s souring approval ratings could damage their political fortunes even in deep red states.

The Democratic Congressional Campaign Committee announced that it would launch as many Facebook ads as possible about the incident, targeting Montana Democratic voters who might not otherwise vote Thursday. The Committee also said Gianforte must quit the race and the Republican Party should publicly denounce him.

Requests for comment went unanswered Wednesday night from House Speaker Paul Ryan and the National Republican Congressional Committee.

Scott Sales, the Republican president of Montana’s state senate, unsuccessfully vied against Gianforte for his party’s congressional nomination. On Wednesday evening, he said he could not understand why the scuffle took place.

“There’s always two sides to a story, but this doesn’t look good,” Sales said. “It’s not what you want to see happen on the eve of an election.”

The Gianforte campaign Wednesday night released a statement blaming the incident on Jacobs. It contends he “aggressively shoved a recorder in Greg’s face and began asking badgering questions” before being asked to leave.

Gianforte asked Jacobs to lower a phone that was being used as an audio recorder, then tried to grab it, the campaign said in a statement. Jacobs then grabbed Gianforte’s wrist and both fell to the ground, Scanlon said.

The 45-second recording does not contain a request from Gianforte that Jacobs lower his phone. Acuna, the Fox News reporter, wrote that “at no point did any of us who witnessed this assault see Jacobs show any form of physical aggression toward Gianforte.”

Gianforte had been scheduled to attend a meet-and-greet with campaign volunteers at his headquarters in Bozeman, but he left early.

As a candidate, he has already had to apologize for his treatment of the press after an incident last month at a meeting of a Christian group where a man complained about reporters and said he wanted to “wring their necks.”

Gianforte pointed out a reporter covering the meeting and said, “It seems like there is more of us than there is of him,” according to the Helena Independent Record newspaper. He later said it was a joke and the reporter in the room laughed with everyone else.

Hours before the incident on Wednesday the Gianforte campaign sent out a last-minute fundraising appeal to its supporters, saying the outcome “will determine whether we pass Donald Trump’s America First agenda or if the fake news media and the national Democrats will win, keeping Obama’s reckless policies in place,” the plea said.

The Guardian is a British liberal newspaper that opened a U.S. edition 10 years ago. Its U.S. editor, Lee Glendenning, said in a statement: “The Guardian is deeply appalled by how our reporter, Ben Jacobs, was treated in the course of doing his job as a journalist while reporting on the Montana special election. We are committed to holding power to account and we stand by Ben and our team of reporters for the questions they ask and the reporting that is produced.”