But on many key votes, her record is about as moderate as Ted Cruz’s. In January, she provided the Republicans with the crucial 51st vote for the tax bill. She set three conditions: the additional passage of two separate bills to shore up insurance markets for individuals who weren’t covered through their work, along with a promise for Congress to undo the cuts to Medicare automatically triggered by the deficit increase from the tax cut.

After that bill was passed, Ms. Collins said the promises to her were ironclad, and that if her conditions were not met, “there would be consequences.” But the additional bills never got a vote, and a follow-up attempt to add her provisions to the omnibus spending bill in March was defeated, by other Republicans.

Of course they were.

As a voter in Maine for the last 30 years, I’ve been represented by a broad spectrum of independent statesmen and women. During my first year living here, we had dinner in a Skowhegan restaurant called the Heritage House, and at the table next to ours was Margaret Chase Smith, who, of course, stood up against the tactics of Joseph McCarthy in 1950 with her “Declaration of Conscience” speech. We stood up to shake her hand. I still remember that moment, the sparkle in her fierce eyes. It was like looking directly into history.

We’ve been represented by other mavericks in the last half-century. Senator William Cohen, another Republican, served as the secretary of defense for a Democratic president, Bill Clinton. George Mitchell, a former Senate majority leader, helped to bring about the Good Friday peace accords in Ireland, and was nominated for the Nobel Peace Prize. For eight years we had an independent governor, Angus King, who has gone on to represent our state as an independent in the Senate. (My wife and I are public supporters of, and have a long friendship with, the Kings.) Being independently minded is a tradition in Maine, as much a part of who we are as lobsters, moose hunting and whoopie pies.

But there are different ways of being a maverick. For Smith, it meant taking a stand, opposing McCarthy at the apex of his power. For Arizonan John McCain, it meant voting against the repeal of the Affordable Care Act, at least when no provisions had been made for the 20 million Americans who would have suddenly found themselves without health care.