Gov. Paul R. LePage, a Republican running for a second term, defeated his Democratic opponent, Representative Michael H. Michaud, who conceded the race shortly after midnight.
Voters rebuffed appeals from nationally prominent Democrats, including President Obama and Hillary Rodham Clinton, who appeared on stage at campaign rallies for Mr. Michaud in the last few weeks.
Mr. LePage, the blunt-spoken, tough-talking former mayor of Waterville, had often been listed as one of the nation’s most endangered governors. Maine Democrats called him a national embarrassment. But his conservative agenda, including a promise to trim state budgets and reduce welfare rolls, evidently resonated with voters.
White House officials had assumed that if Mr. Michaud won, Maine would quickly agree to expand Medicaid, as Mr. Obama wants. Mr. LePage has vetoed several efforts to do just that.
Gov. Chris Christie of New Jersey, the chairman of the Republican Governors Association, visited Maine several times to help Mr. LePage, and the association poured money into the state to support that effort.
In one of the least surprising results of this year’s elections, Senator Susan Collins, a centrist Republican, won her fourth term, handily defeating the Democratic contender, Shenna Bellows.
Ms. Bellows, making her first run for elective office, had a number of successes as executive director of the American Civil Liberties Union of Maine for the last eight years. As a candidate, she was energetic, but no match for Ms. Collins, whose stature has steadily increased over 18 years in the Senate. Ms. Collins had a fund-raising advantage over Ms. Bellows and won endorsements from some labor unions and environmental and gay rights groups, which more often favor Democrats.
During the campaign, Ms. Collins endorsed same-sex marriage and said it was probably too late to repeal the Affordable Care Act. She voted against that health care legislation five years ago and says she now wants to fix its flaws.
—ROBERT PEAR