Being governor is about the best job in politics. You get to live in or near your home. The extreme partisanship of Washington usually doesn’t exist in state capitals, so you can accomplish things that materially affect people’s lives. You get the trappings of a chief executive without the burdens of the presidency.

Being in Congress, on the other hand, is arguably the worst job in politics. You live apart from your family or travel back and forth, spending endless time in airports and on planes. Extreme partisanship, grandstanding and gridlock are the rule on Capitol Hill. And while every senator may look in the mirror and see the next president of the United States, that’s rarely the case, and virtually never true for members of the House. It’s political purgatory — endless waiting with a creepy cast of characters.

Logically, you’d think that an overwhelmingly popular senator would grab the chance to return home and run for governor rather than stay in the toxic atmosphere of today’s Senate. But then Sen. Susan Collins (R-Maine) is the exception to many rules of 2017 politics — a moderate in an era of no moderation, a policy enthusiast in an era of stupid slogans, a figure very much respected and even loved by those on the other side of the aisle and one of the lone, responsible GOP senators who would not agree to massive cuts in Medicaid and a hodgepodge health-care bill that likely would have left her constituents (especially in rural Maine) less well-off. It then should not have been a huge surprise that Collins announced this morning that she would remain in the Senate rather than make a run for the governorship of Maine.

There’s a logic to her decision. At a time when President Trump is in office and the Senate is getting populated with more and more unhinged characters, she plays a vital role as a grown-up. Think of Justice Anthony Kennedy on the Supreme Court. Since everyone else on the court is so predictable, in controversial cases the question for litigants is most often: What would Kennedy decide? So, too, in an evenly divided Senate, as we saw in the health-care debate, the issue may often come down to: What would Collins want?

Contrary to the GOP’s expectations, Republicans (thanks to Trump and to Stephen K. Bannon’s GOP civil war) may not pick up Senate seats in 2018. It even may lose one or two on net considering how badly Sen. Jeff Flake (R-Ariz.) is polling and how vulnerable Sen. Dean Heller (R-Nev.) is. It’s therefore quite possible that the Senate may be 51-49 or even 50-50. (It’s hard but not impossible to imagine Democrats actually winning a majority.) In other words, Susan Collins could be even more influential after 2018 than she is now — maybe the deciding vote on everything from Supreme Court nominations to tax reform to Iran sanctions.

How then could she choose to use her influence over the next few years?

She certainly could pursue a reasonable health-care compromise along with Sens. Lamar Alexander (R-Tenn.), Lisa Murkowski (R-Alaska) and John McCain (R-Ariz.). She could refuse to vote for any debt-creating tax reform bill, as Sen. Bob Corker (R-Tenn.) has done. She can vote no on obviously unqualified or extreme nominees. In the Senate one person can make a huge difference, and if she puts her mind to it, she might be able to exercise considerable influence to pull the party back from the brink and toward the center.

She could also seek to influence the Senate itself, pushing the leadership to preserve the “blue slip” process for judicial appointments, refusing to vote for any legislation that does not go through regular order, etc. When you are the deciding vote on a whole bunch of legislation, you get a lot of influence.

Most of all, she could set the standard for Congress’s interaction with Trump. She could lead the way in checking his abuse of power and require he abide by rules that every president has followed. She can surely team with Democrats and some sensible Republicans to push for mandatory release of presidents’ taxes (she could even delay its effect until 2020), for a president’s annual mandatory physical and mental-health checkup, an absolute bar on relatives working in the White House and disclosure, if not full divestiture, of presidential holdings. She can use her sway for censure votes next time Trump winks at neo-Nazis or denigrates the First Amendment.

And then there is impeachment, the 25th Amendment and the special counsel’s report. As one of the few Republicans willing to ignore partisan pressure, she can be a powerful voice when and if she believes the president cannot fulfill his oath of office. She can urge the House (if it’s still in GOP hands) to take up impeachment hearings if and when she thinks that is warranted. She can question in open or closed sessions current or former senior aides to assess the president’s mental and emotional state.

In other words, she can do the job that every single Republican should do but refuses to do out of fear, moral paralysis or partisan loyalty. Nothing I have listed is extraordinary; it should be the minimum to expect from each and every Republican. But, of course, virtually none of them will meet such a standard of conduct.

She alone cannot change our politics, but she can move the needle in the Senate and perhaps inspire fellow Republicans to do their jobs. Hey, that would be something — and almost make bearable the task of listening to Sen. Ted Cruz (R-Tex.) and others pontificate for hours on end. Almost.