Ms. Collins had been debating running for the open seat in her state for some time.
Collins, who is serving her fourth term in the Senate, said in her home state of ME that though Congress is marred with dysfunction, she ultimately decided that she had much left to accomplish on Capitol Hill. Her Senate term runs through 2020. She introduced a bill to let transgender people serve in the military and opposed efforts to kill the Affordable Care Act without a replacement.
As one of the few remaining moderate Republicans in the Senate, Collins' departure would have left a noticeable mark on the politics of the chamber.
Collins doesn't shy away from her role in the middle. Additionally, Collins would have control of the state bureaucracy, potentially using it and the bully pulpit of the governor's office to advance a policy agenda to work on initiatives that could improve Maine's economic outlook.
Collins, 64, is popular in ME, having won reelection in 2014 with 68 percent of the vote.
The 64-year-old Collins has been weighing for months whether she'd make a bigger impact in the Senate or by launching a bid to become the first woman to serve as Maine's governor.
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