He congratulated Ayotte on Wednesday and says he is disappointed but humbly accepts the result. He had the option of asking for a recount because his loss margin was within 1.5 percent of the total votes cast.
The secretary of state's office said Wednesday that Ayotte had won by 1,667 votes. She had been backed by former Alaska Gov. and vice presidential nominee Sarah Palin.
Lamontagne is a conservative Manchester lawyer.