MILBRIDGE, Maine (AP)   Her next election may be more than two years away, but Republican Sen. Susan Collins has a challenger.

Dr. Cathleen London, a largely unknown Democrat from Milbridge, announced this week that she’s going to seek her party’s nomination to challenge Collins in 2020.

She criticized Collins for saying she wouldn’t use any litmus tests for Supreme Court nominees and for her support of the Republican tax reform bill. London said that when it comes to tough decisions Collins puts President Trump and her party ahead of her Maine constituents.

She was a college professor in New York City and had a practice in Brookline, Massachusetts, before coming to Maine three years ago.

Collins, who was first elected in 1996, declined comment. She hasn’t officially said if she’s seeking another term.