From the Great Falls Tribune:
The Associated Press and national TV networks had still not called the race shortly after 7 a.m., in part because of uncertainty over the vote totals in Democratic stronghold Butte-Silver Bow County.
The Associated Press was checking into whether the Silver Bow count was missing some votes. As reported in early returns, Tester had 6,703 to Burns’ 2,996.
But based on the turnout statewide, which approached the 60 to 70 percent turnout in presidential election years, the Silver Bow count appeared to be lacking about 4,000 votes.
Meagher County was the only county not reporting results Wednesday morning. Election officials there said the nearly 900 ballots cast in the rural county were being counted by hand, and results were expected later this morning.