Gianforte has extended his lead to 51 percent to 46 percent, according to the Montana Secretary of State.
NBC News has declared Gianforte the winner, but The Associated Press has not made a call.
Click here for updated numbers.
Update 10:05 p.m. Gianforte has pulled into a slight lead with 76,412 to 76,088 for Williams.
Democratic challenger Kathleen Williams took an early thin lead in the U.S. House race, 49-48 percent.
Libertarian Elinor Swanson had 3 percent.
About 59,000 ballots had been counted by the Montana Secretary of State’s office.
Check back for updates.
Republican Congressman Greg Gianforte is running for his first full term in the U.S. House.
Gianforte is a former software company founder who moved to Bozeman in the mid-1990’s. He and his wife Susan co-founded RightNow Technologies. The company employed more than 500 people when it was sold to Oracle Corp. in 2012 for $1.8 billion.
He sought the Governor’s Office in 2016, but was defeated by incumbent Democrat Steve Bullock.
Gianforte first won Montana’s sole congressional seat in a May 2017 special election — the day after he threw to the ground and punched reporter Ben Jacobs of the Guardian, at a campaign event in Bozeman. Gianforte later pleaded guilty to misdemeanor assault.
He has closely aligned himself with President Trump and the administration’s policies. He backed the 2017 GOP tax-cut bill, supports increased military spending and securing the border.
Democrat Kathleen Williams, also from Bozeman, challenged Gianforte for the seat.
She moved to Montana in the 1990’s.
Williams served in the Montana Legislature from 2011 to 2016 before winning a surprise victory in the six-way Democratic U.S. House primary.
Her primary focus while running has been on fixing health care and she said she would have voted against the GOP tax-cut bill.
She also highlighted her record in the legislature including her work on bills that required health insurers to cover the cost of clinical trials for cancer patients and one that enabled the creation of more local retail-food producers.
Libertarian Elinor Swanson also appeared on the ballot.
Reporting by Jon Stepanek for MTN News