Republican U.S. Sen. Susan Collins announced Friday that she won’t run for governor because she believes she can do more good by remaining in Washington, where she serves as an important swing vote.

Her announcement was welcomed by supporters who view her as an important check on President Donald Trump, with whom she’s crossed on the GOP’s health care proposal.

“My voice and vote really matter in Washington right now. The Senate is closely divided and I am able to make a difference,” Collins, 64, told The Associated Press after a local chamber breakfast.

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. Collins acknowledged it was a difficult decision, one that she’d struggled over.

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. But she’s not afraid to buck her own 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.

In Washington, she’s been a consistent thorn in the side of Republican Senate Majority Leader Mitch McConnell, as her willingness to go her own way has left him short of votes on key bills, most prominently his efforts to repeal “Obamacare.”

On Friday, McConnell praised Collins for choosing to remain in the Senate, saying she “brings conviction, smarts and leadership to every issue.” Maine’s other senator, independent Angus King who caucuses with the Democrats, called her “a champion for the state of Maine.”

Collins spent much of her announcement touting the importance of finding bipartisan solutions to make health care affordable for all. She said her fellow lawmakers “must stop allowing partisanship to be a pre-existing condition.”

Collins was one of three Republican senators who sunk the Republican Senate health care bill. She also serves key roles on the Appropriations Committee and on the Intelligence Committee, which is investigating Russian meddling in the 2016 presidential election.

She’s embraced her role as a centrist who bridges the gap and will keep that role in a Senate that’s likely to remain bitterly divided as ever in the years ahead.

“When you’re in the center, you expect that you’re going to get attacked from both the far left and the far right, and I certainly have been,” she said. “But there are still people on both sides of the aisle on specific issues who are willing to come together in the middle.”

Her decision will likely free more gubernatorial candidates who have been waiting on the sidelines to enter the race. Republican Gov. Paul LePage cannot run again because of term limits.

The gubernatorial race is already a crowded field, with more than a dozen members of the Republican and Democratic parties having announced primary runs.

If she’d chosen to run for governor, Collins said, she was confident she could have won the GOP primary and the general election, despite LePage’s criticisms that she’s not conservative enough. She dismissed LePage’s complaints, saying he didn’t have an impact on her decision.

Collins said most Americans are moderates like herself — and need to speak up and become “fanatical moderates” to ensure Congress represents their interests.

In Washington, she said, she’s going to maintain a positive outlook despite partisan fights and a series of disagreements with Trump. She didn’t vote for him in November, despite his being on the Republican ticket.

“I am a congenital optimist. I continue to believe that Congress can, and will, be more productive,” she 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.”

(AP)