Republican U.S. Sen. Susan Collins announced Friday that she's staying out of the governor's race because she believes she can do more good for Maine by staying in Washington.
"I am a congenital optimist. I continue to believe that Congress can, and will, be more productive," Collins said. "I want to continue to play a key role in advancing policies that strengthen our nation, help our hardworking families, improve our health care system, and bring peace and stability to a troubled and violent world."
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. She is one of a handful of GOP centrists and decided she's needed in the U.S. Senate.
Her decision will likely free more gubernatorial candidates who have been waiting on the sidelines to enter the race.
Two-term Republican Gov. Paul LePage cannot run again because of term limits.
Like President Donald Trump, LePage has been a polarizing leader. Collins said previously that she'd like to heal the state and "bring people back together."
Speculation about Collins' political future has been swirling for more than a year in her home state, where the moderate remains popular even as the Maine GOP has become more conservative.
She has been a champion for those who want to hold Trump in check: She was one of three Republican senators who sunk the Senate health care bill pushed by his administration. She also serves key roles on Appropriations Committee and the Intelligence Committee investigating Russian meddling in the 2016 presidential election.
The only Republican senator from New England has found herself among a dwindling number of GOP centrists like Arizona's John McCain who are willing to work across the aisle.
She's not afraid to buck her party. She introduced a bill to let transgender people serve in the military and opposed efforts to kill the Affordable Care Act without a replacement.
Collins, who has served for two decades in the Senate, was part of the Gang of 14 bipartisan senators that prevented the so-called nuclear option by Senate Republicans over an organized use of the filibuster by Senate Democrats.
Collins doesn't shy away from her role in the middle. She has called for "fanatical moderates" to serve as an antidote to extremes of both parties in Washington.
But her role has left her open to fire from both the right and the left.
And she's on the outs with Trump. She said she couldn't bring herself to vote for him, and she criticized him for failing to speak out more forcefully against racism, bigotry and anti-Semitism following the death of a woman at a white supremacist rally in Charlottesville, Virginia.
Collins grew up in Caribou, in far northern Maine. The middle of six children learned the importance of hard work by age 10 while plucking potatoes from the dirt for 30 cents per barrel. The only political race she lost was for governor, in 1994.
She has won her last few elections handily. She was re-elected with 68.5 percent of votes in 2014, 61.3 percent in 2008 and 58.4 percent in 2002. Her current term ends in 2020.
Some of her supporters were worried that leaving the Senate would have left Maine's pugnacious governor to appoint her replacement. But Maine constitutional law expert Marshall Tinkle said she wouldn't have to resign to run and could pick her successor after being sworn in.
Maine's 2018 gubernatorial race could be a referendum on the legacy of LePage, whose administration slashed entitlement growth and touts a healthy state surplus. For all his successes, though, LePage is known for his bombastic leadership style.
LePage criticized Collins this year for saying Indiana's plan to expand Medicaid could be a model for Maine.