Neither strayed far from the lines of attack they have used during the early months of the campaign and stayed on message on key areas of difference.
Both candidates gamely and competently answered questions posed by a three-member panel of broadcasters during the debate carried live on radio and by some television stations. The question-and-answer format left little opportunity for both candidates to engage aggressively with one another.
"There were no knock-out blows," said David Parker, a professor of political science at Montana State University.
In his first debate, Gianforte was collected and composed. Bullock was assertive and confident.
"Greg Gianforte came in as never having run a race before. So expectations were low, and he came off in the debate as calm and acceptable," Parker said.
Bullock's performance Sunday was a marked improvement from four years ago, Parker said, when Bullock seemed less steady. "This time, I think he came across as confident and accomplished."