SWAMPSCOTT, Mass. — The man who lives in the white house made an announcement the other day that might stand as a turning point in American politics.

That may sound overdramatic, given that the white house in question belongs to the governor of Massachusetts, even though his home – right across from town hall and a few hundred feet from King’s Beach in this small shore town – possesses a protuberance that bears a slight resemblance to the Truman Balcony on Washington’s White House.

But Charlie Baker’s announcement that he won’t seek a third term on Beacon Hill sent out shock waves that reached Capitol Hill, and that might stand as a monument in our national passage.

Years from now, Gov. Baker’s demurral may be seen as the moment a certain strain of Republican vanished from American politics. It came the same week as Rep. Marjorie Taylor Greene of Georgia, who has promoted some of QAnon’s conspiracy theories, declared that she and her allies “actually represent the base of Republican voters,” a notion that Democrats will not hesitate to embrace in their campaign appeals in next year’s midterm congressional elections.

The age of the moderate Republican – the conventional Republican, the straight-laced Republican – now may be officially over.

Mr. Baker had stratospheric approval ratings, tying him with GOP Gov. Mark Gordon of Wyoming as the nation’s most popular state chief executive, according to a Morning Consult survey – although Mr. Baker, unlike Mr. Gordon, was far more popular with Democrats than with Republicans. Indeed, he was facing a challenge from the right from a former state representative, Geoff Diehl, who has the support of former President Donald J. Trump. The governor did not vote for Mr. Trump in either 2016 or 2020, essentially leaving his ballot blank.

Mr. Baker’s statement, issued with his lieutenant governor, Karyn Polito, included the usual proud-to-have-served rhetoric and recitals of their accomplishments, which included a cut in the state income tax and a boost in the state’s reserve fund.

Taxes are cut and reserve funds bolstered every few years across the country, but a megastar governor doesn’t vanish from public life every day. Two of his gubernatorial predecessors, Michael Dukakis and Mitt Romney, were presidential nominees.

Mr. Baker’s withdrawal came in the same week that a range war broke out among House Republicans after Rep. Nancy Mace of South Carolina criticized a colleague, Rep. Lauren Boebert of Colorado, for suggesting that a third lawmaker, Democratic Rep. Ilhan Omar of Minnesota, a Muslim woman who wears a hijab, appeared to resemble a terrorist. Ms. Greene then described Ms. Mace as “the trash in the GOP conference.” That same week, Ms. Greene introduced legislation to give the Congressional Gold Medal to Kyle Rittenhouse, recently acquitted after employing a semi-automatic weapon to shoot three people, killing two of them, during unrest in Kenosha, Wisconsin.

Democrats, not wishing to disrupt a moment of opportunity for themselves, simply watched the contretemps escalate. They have their own difficulties, with a progressive wing of the party constantly at odds with a more conservative strain.

But for a few days, the Democrats’ woes were sublimated by the Republicans’ disputes, and the withdrawal of Mr. Baker seemed to underline the other identity crisis in American politics.

The new Republicans, inspired and motivated by Mr. Trump, bear almost no resemblance to the Republicans of a generation ago, who were inspired by Ronald Reagan, whose battle against communism abroad and big government at home was the leitmotif of the age. Nor do they bear the faintest resemblance to the Republicans who arrived in Washington before Reagan and who – sometimes eagerly, more often reluctantly – adapted to the new Republican regimen.

These Republicans – Howard H. Baker Jr. and Bob Dole, for example, two men who both were for a time Senate majority leaders and then presidential candidates, with Dole winning the party’s nomination in 1996 – were conservative but had an instinct for compromise. Mr. Dole was no reluctant partisan pugilist, but he was more comfortable with his identity as a dealmaker, a political figure who won results rather than debating points.

John F. Kennedy courted Rep. William M. McCulloch of Ohio to win GOP support for his civil rights legislation, which eventually passed after the 35th president’s death. “You made a personal commitment to President Kennedy in October 1963 against all the interests of your district,” Jacqueline Kennedy Onassis wrote Mr. McCulloch years later. “When he was gone, your personal integrity and character were such that you held to that commitment despite enormous pressure and political temptations not to do so.”

In Massachusetts, moderate Republicans such as John A. Volpe (1961-1963 and 1965-1969), Francis W. Sargent (1969-1975), William F. Weld (1991-1997), Paul Cellucci (1997-2001) and Mr. Baker were popular governors in a state that voted for a Democrat in 16 of the last 20 presidential elections.

But that strain of Republican has disappeared, and there is no stronger evidence of the fading of that genus and species of the GOP than the recently published journal of Rep. Barber B. Conable Jr., the 11-term lawmaker from New York and longtime ranking minority member of the Ways and Means Committee. Mr. Conable personified the Republicanism of the old school: conservative, but not unwilling to compromise.

He was a leading figure in the 1982-1983 effort to preserve Social Security. In the pages of his journal, he wrote he was “personally convinced that if we did not have that issue behind us, it might be the end of the two-party system when Republicans, who handled [the Social Security] issue so badly, went onto the presidential election advocating something that could be interpreted as a cut in benefits.”

Then he added a sentence no American politician would write today:

“In short, I do not see this as a victory for moderation over extremism, [but] as a true political compromise achieving a very necessary settlement of an issue too emotional to be handled comfortably or even safely by the Congress.”

Mr. Conable, who lived in the tiny western New York town of Alexander, died in 2003. It is not too much to say we will not see his like, or Charlie Baker’s, again anytime soon.

David M. Shribman is the former executive editor of the Pittsburgh Post-Gazette.

First Published December 5, 2021, 12:30am