WASHINGTON, D.C. – Washington is a lonely place for Maine’s Sen. Susan Collins these days.

The president is a fellow Republican, but her pointed criticism of Donald Trump doesn’t make for a chummy relationship. Her party controls both the House and Senate, but she’s a moderate island in a stormy sea of partisanship.

On one of the most crucial votes held so far, the confirmation of Neil Gorsuch to the Supreme Court, she stuck with her party.

Now, observers in Washington and Maine will be watching to see how often she will break with her party, if she will be outspoken on issues like the investigation into Russia’s meddling in U.S. politics and whether the new political dynamics here in the nation’s capital will make her more or less important.

“She puts herself forward as an independent-thinking, practical, reasonable senator who doesn’t just do what her party tells her to do,” says political scientist Thomas Mann, a senior fellow at the left-of-center Brookings Institution and a resident scholar at the University of California, Berkeley. “This period poses a test for her and her reputation.”

Collins says she can be successful in this new environment, that it’s just a more difficult one.

“It’s getting much harder because the center is melting like spring snow in Maine,” she says.

Proud of being rated the most bipartisan senator by the Lugar Center at Georgetown University, Collins adds, “I believe we need to respect differing views and try to work out solutions.”

Republicans have a slim majority in the Senate. If just three of its 52 senators stray, the party loses its edge. To congressional scholar Josh Chafetz, a law professor at Cornell University, that means the GOP needs Collins more than she needs it.

Even though Collins voted for Trump’s Supreme Court nominee, “she’s not an automatic ‘yes’ to what Trump wants,” Chafetz says. On the other hand, he says, there haven’t yet been enough key votes yet to see whether Collins’ moderation is more than just talk.

Her Maine colleague, Sen. Angus King, an independent who caucuses with Democrats, says that he expects she’ll vote with Republicans more often than not but that “she’s not a lock” for her party.

Collins points out that while almost all her GOP colleagues voted to confirm every Trump nominee, she voted against two, Education Secretary Betsy DeVos and Environmental Protection Agency head Scott Pruitt, and successfully pushed for the withdrawal of Labor nominee Andrew Puzder.

During the presidential campaign, Collins not only didn’t endorse Trump but also said he was unsuitable for the Oval Office. Since his inauguration, they’ve had just one conversation, about health care. Collins came out against a House bill to repeal Obamacare and the House leadership eventually tabled it.

Although Collins and the president are anything but close, the White House has reached out to her through first daughter Ivanka Trump and Vice President Mike Pence. The vice president invited Collins to dinner with other senators and asked for her input before the administration chose Gorsuch.

Collins, who serves on the powerful Appropriations Committee that allots funding, says she is unhappy with the new administration’s “meat ax” approach to cutting federal agencies, especially the EPA and the National Institutes of Health. She vows to work across party lines to minimize the cuts.

King, meanwhile, says Collins’ seniority on Appropriations committee gives her considerable power. The closely divided Senate means “she has to be part of the equation,” he added, saying “that gives her a great deal of influence.”

Yet Mann, the Brookings political scientist, said he doubts Collins will be able to advance the moderate positions she cares about in a Capitol controlled by conservative Republicans.

He is watching to see whether Collins burnishes her moderate reputation by, for example, speaking out on Trump’s continued refusal to release his tax returns and doggedly pursuing the investigation into Russia’s meddling in the U.S. presidential elections.

A member of the Senate Intelligence Committee, Collins says she intends to follow the evidence wherever it leads. Democrats have called for an independent investigation, but Collins notes that the Intelligence Committee already has the necessary security clearances to look into whether Trump advisers collaborated with Russia. She says she agrees with the criticism that the panel does not yet have enough trained investigators.

Sen. Mark Warner, D-Virginia, the vice chairman of that committee, said Collins has played a vocal and key role behind closed doors. “You’ve got this constant tension where some on the Republican side want this to go away and some on the Democratic side want indictments tomorrow,” Warner says. “She’s got credibility with both sides in a place few have that, in an investigation so potentially explosive. She has earned that.”

According to Collins, the nation is in need of more “fanatical moderates.” She says that she believes she represents quiet centrists in this era of loud partisanship.

But hyper-partisanship is not what will push Collins into leaving Washington to run for governor, if she decides to do that. She says she hadn’t made a decision but is weighing the hands-on opportunity to create jobs and help education policy in Maine against her opportunities in a Senate where she already ranks 15th in seniority.

“In some ways,” Collins says, “I feel my role in D.C. is more important than ever. There are still those of us who believe the best legislation is a compromise, it’s not a sellout. “

Tamara Lytle is a longtime Washington correspondent.