ROCKPORT, Me. — After several months of open deliberations about her future, Senator Susan Collins of Maine announced Friday that she would not run for governor and would remain in the Senate.
Ms. Collins, a Republican who was first elected to the Senate in 1996, has become a thorn in the side of President Trump, for whom she did not vote. Most famously, she played a crucial role this summer in dooming his goal of repealing the Affordable Care Act.
Since April, Ms. Collins, 64, has toyed publicly with the idea of running for governor, which was the first office she ran for, in 1994. Though she lost that race, she said she was still drawn to the ability of a governor to have a direct and immediate effect on people’s lives by creating jobs and spurring economic development. She also said she felt an affinity for Augusta, the capital, where a long line of ancestors served in the State Legislature, starting with her great-great grandfather and including her father.
Had she run and won the race for governor in 2018, she would have become the first woman in Maine to hold the office.
Although she has been one of Maine’s most popular politicians for some time, there was no guarantee that she would win her party’s nomination in the June primary. Gov. Paul R. LePage, a fellow Republican who is barred by term limits from seeking a third term, has been stirring the political pot against her. Ms. Collins, a moderate who has glided to victory in her recent elections, this time faced the likely prospect of bruising and expensive attacks from the right.
Now in her fourth term in Washington, she ranks 15th among the 100 senators in seniority and appears to be at the height of her power. As one of the few moderates in a closely divided Senate, she is often a swing vote, and, as she demonstrated during the health care debate, she can often influence the outcome of important legislation. Since Mr. Trump became president, she has voted less often with her party than any other Republican senator.
By staying in the Senate, Ms. Collins “can continue to have a pretty interesting role as one of the few people who isn’t in lock step with one party,” said Stuart Rothenberg, a veteran political analyst for Inside Elections With Nathan L. Gonzales, a nonpartisan newsletter that analyzes campaigns.