(CNN) Until now, Greg Gianforte, a candidate in Thursday's special congressional election in Montana, was known as a multimillionaire tech entrepreneur who once ran for governor.

But the Republican redefined himself Wednesday when he was charged with misdemeanor assault after allegedly body slamming a reporter just hours before the polls open.

Gianforte, whose campaign has enjoyed strong support from President Donald Trump, is making a bid for Montana's lone seat in Congress, which was vacated when Republican Ryan Zinke became Trump's interior secretary. Some see this race as a referendum on Trump's young presidency

Tech guru enters politics

Gianforte, 56, started RightNow Technologies decades ago from his home in Bozeman, and sold it to Oracle in 2012.

He mounted a failed bid last year for Montana governor, spending an estimated $5.1 million of his own money on the race.

Asked why he wants to serve in Congress, Gianforte told CNN that he would be a "strong voice for Montana in DC." He also talked about raising four kids in Montana.

In this race, Gianforte has raised about $2.3 million, compared with his Democratic opponent, Rob Quist, with $3.3 million, Federal Election Commission records show. Gianforte also lent his campaign $1 million.

Trump backs candidate

The Trump administration has lent plenty of support to Gianforte. Vice President Mike Pence and Donald Trump Jr. both have campaigned for him, and the President just recorded a robocall in a push to turn out GOP voters.

"Hi, this is President Donald Trump, and I know what the people of Montana really want and really care about," he says in the recorded call. "If you don't vote ... the liberal Democrats running for Congress will decimate and dismantle all that we've done. ... So get to the polls and vote for Greg. ... You'll be very proud of him for years to come."

Montana is Trump country, having voted 57% to 36% for him over Hillary Clinton in the November election. But on the same night, Montanans also re-elected Gov. Steve Bullock, a Democrat.

Endorsements pulled

The altercation with the journalist unfolded Wednesday at Gianforte's campaign headquarters in Bozeman.

Gianforte allegedly body slammed Ben Jacobs, a reporter for The Guardian, and broke his glasses, according to an audio recording of the event and eyewitness accounts.

"He took me to the ground," Jacobs said.

But Gianforte's campaign said Jacobs acted aggressively toward the candidate, shoved a recorder into his face, grabbed him by the wrist and pulled them both to the ground.

Gianforte received a citation and is scheduled to appear in Gallatin County Justice Court before June 7, the sheriff's office said.