However, the Maine Republican said, President Trump should be "afforded the opportunity" to challenge the election results.
A Trump-fueled turnout surge capped a GOP comeback over the final month of the campaign.
The Republican senator has won re-election against Democrat Sara Gideon.
Collins faced the toughest reelection bid of her career. Her win gives Republicans a key victory in their effort to maintain control of the Senate.
Some election experts say the state's unconventional voting system could spell trouble for the embattled Republican.
Republican incumbents are straining for survival from New England to the Deep South, in the heartland and the West and even Alaska.
The Republican senator should apologize for dismissing "our concerns and our pain," said one Black Lives Matter activist in Maine.
The 48-year-old Trump-picked judge is now one vote away from serving on the high court and solidifying a 6-3 conservative majority for the foreseeable future.
Experts say Maine's ranked-choice voting system could hurt the Republican senator's reelection chances.
The Christian Civic League of Maine supports conversion therapy and opposes gay marriage — and the Republican senator is thrilled to have its support.