BOZEMAN, Mont. -- Republican multimillionaire Greg Gianforte won Montana's only U.S. House seat Thursday despite being charged a day earlier with assault after witnesses said he grabbed a reporter by the neck and threw him to the ground.

Gianforte cruised to victory after weathering a political firestorm, observes CBS Billings affiliate KTVQ-TV. He won 48 of Montana's 56 counties, the station notes.

Gianforte, a technology entrepreneur, defeated Democrat Rob Quist to continue the GOP's two-decade stronghold on the congressional seat. Democrats had hoped Quist, a musician and first-time candidate, could capitalize on a wave of activism following President Trump's election.

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Instead, the win reaffirmed Montana's voters support for Mr. Trump's young presidency in a conservative-leaning state that voted overwhelmingly for him in November.

Montana Democratic congressional candidate Rob Quist stands with wife Bonni, left, and daughter Halladay while giving his concession speech in Missoula after Republican rival Greg Gianforte beat lhim in special election on May 25, 2017 Stringer

Gianforte was a strong favorite throughout the campaign and that continued even after authorities charged him with misdemeanor assault Wednesday. Witnesses said he grabbed Ben Jacobs, a reporter for The Guardian newspaper, and slammed him to the ground after being asked about the Republican health care bill.

At least two major Montana newspapers, the Billings Gazette, in the state's largest city, and the Missoulian, in Missoula, Montana's second-largest city, announced late Wednesday they were rescinding their endorsements of Gianforte.

Jacobs reported in April that Gianforte has financial ties to Russian companies that have been sanctioned by the U.S.

CBS News Elections Director Anthony Salvanto said that, based on CBS News estimates as the vote was coming in, there didn't appear to be a large difference between the early/mail vote and Election Day vote overall. And turnout was comparable to that of a midterm election.

With some 97 percent of the vote counted, Gianforte had 50 percent of the vote, Quist had 44 percent and Libertarian Mark Wicks had six percent. Turnout was almost 54 percent of registered voters.

Greg Gianforte and wife Susan hug after he delivered his victory speech in Bozeman, Montana following a special congressional election on May 25, 2017 Stringer/Reuters

Gianforte dropped out of sight after he was cited by police and ignored calls Thursday by national Republicans for him to apologize to the reporter.

He emerged only at his victory celebration Thursday night, where he said he accepted responsibility for the incident. "Last night I made a mistake and I took an action I can't take back and I am not proud of what happened," Gianforte told the crowd. "I should not have responded the way I did and for that I am sorry."

The last-minute controversy unnerved Republicans, who also faced close calls this year in traditionally Republican congressional districts in Kansas and Georgia. A runoff election is scheduled for next month in Georgia between Democrat Jon Ossoff and Republican Karen Handel after Ossoff fell just short of winning outright.

Quist told supporters he called Gianforte to congratulate him on his win and urge him to represent all Montanans. "I know that Montanans will hold Mr. Gianforte accountable," Quist said Thursday night.

Gianforte showed lukewarm support for Mr. Trump during his unsuccessful run for governor in Montana last fall but did an about-face and turned into an ebullient Trump backer after he started campaigning for the congressional seat vacated by Republican Ryan Zinke when Zinke was tapped by the president to serve as Interior Department secretary.

Gianforte urged Montana voters to send him to help Mr. Trump "drain the swamp," brought in Vice President Mike Pence and first son Donald Trump Jr. to campaign for him and was supported by millions of dollars of ads and mailers paid for by Republican groups.

But the theme of the election shifted Wednesday night when Jacobs walked into Gianforte's office as he was preparing for an interview with Fox News.

Jacobs began asking the candidate about the health care bill passed by the House when the crew and Jacobs say Gianforte slammed him to the floor, yelling "Get out of here!"

Gianforte's campaign issued a statement Wednesday blaming the incident on Jacobs. But on Thursday night, Gianforte apologized both to Jacobs and to the Fox News crew for having to witness the attack. "I should not have treated that reporter that way and for that I'm sorry, Mr. Jacobs."

It had been unclear if Gianforte's assault charge would impact the race. About a third of eligible voters in Montana had already cast their ballots in early voting, and others said it didn't influence their vote.

Shaun Scott, a computer science professor at Carroll College in Helena, said the assault charge was barely a factor in his decision.

"If you have somebody sticking a phone in your face, a mic in your face, over and over, and you don't know how to deal with the situation, you haven't really done that, you haven't dealt with that, I can see where it can ... make you a little angry," Scott said Thursday.

Quist, a popular 69-year-old singer and cowboy poet who was the front man for the Montana's Mission Mountain Wood Band, was helped by money that poured in from across the U.S. as Democrats seek to capture congressional seats that would have been considered safely Republican a year ago.

Gianforte campaigned as a gun-loving Montanan endorsed by the National Rifle Association to build his credibility among hunting enthusiasts and motivate gun rights activists to vote. He echoed the Republican Party mantras of cutting taxes, beefing up the military and securing the country's borders.

Montana overwhelmingly supported Mr. Trump in November, voted in Republican majorities in the state Legislature and elected GOP candidates to four of five statewide elected positions, leaving Gov. Steve Bullock as the only Democratic statewide elected official.

A Democrat has not held the Montana U.S. House seat since Pat Williams departed in 1997 after he decided not to seek re-election.

Quist ran a nontraditional populist campaign that saw appearances by Sen. Bernie Sanders of Vermont. He stuck to issues that have broad appeal in Montana, such as maintaining and improving access to public land. He collected nearly $3.2 million from individual donors across the U.S.

But Quist had to overcome reports of financial problems that included unpaid taxes, a loan default and legal squabbles with a former band member over royalties and a contractor over payments. He tried to turn those negatives into positives by saying his story illustrated problems many Montanans face because of high health care costs.