With all precincts reporting, Democrat Heidi Heitkamp is leading Republican Rep. Rick Berg by only 3,000 votes in the North Dakota Senate race.
Heitkamp has 160,752 votes in the initial count, while Berg has 157,758.
The close margin between the candidates allows for a recount, and Berg has already vowed not to concede the race until one is completed.
"This is a very close election, which is why North Dakota has a process in place to properly count each ballot and officially certify the result," Berg spokesman Chris Van Guilder said Tuesday night.
The recount process will begin Friday, according to the Berg campaign.