Massachusetts politicos spend an inordinate amount of time speculating about what will happen if Elizabeth Warren leaves the Senate to take another position. The subject came up in 2019 during Warren’s run for the Democratic presidential nomination; it resurfaced earlier this year when she was angling to be Joe Biden’s running mate. Now, with the Bay State’s senior senator being bruited for Treasury secretary in the next administration, the topic is alive again.

If Warren resigns her Senate seat, Massachusetts law authorizes Governor Charlie Baker to appoint an interim senator pending a special election. But Baker’s a Republican, and Democrats break out in hives at the thought of even a temporary Republican senator. One of those Democrats, state Representative Mindy Domb of Amherst, last week proposed amending the law to require that any vacancy be filled by an appointee “of the same political party as the person vacating the office.”

That provoked Baker into issuing a rare veto threat. Asked about Domb’s amendment, the governor called it an example of the “situational dynamics around this stuff when it comes to process associated with elections.” That’s Baker-ese for “political parties brazenly changing the rules whenever it will benefit them.” Such brazenness has emerged as a specialty on Beacon Hill, where, as the Boston Globe reported in 2016, “the basic rule for filling vacancies seems to [be] something like: ‘whatever helps Democrats the most.’”

For a long time, Massachusetts Democrats were content with the system established in 1913, when the 17th Amendment, providing for the direct election of senators, was added to the Constitution. In the event of a Senate vacancy, state law empowered the governor to appoint a replacement who would serve until the next statewide election. When John F. Kennedy resigned from the Senate after winning the 1960 presidential election, for example, Governor Foster Furcolo selected Kennedy’s Harvard roommate, Benjamin Smith, to keep the seat warm until the 1962 election. By then, JFK’s kid brother, Teddy, was old enough to run for the Senate.

But in 2004, things changed. Senator John Kerry was running for president, and Republican Mitt Romney was in the governor’s office. If Kerry were to win, Romney would get to appoint a new senator to serve until the next general election.

So Ted Kennedy — by then the longest-serving senator in Massachusetts history — lobbied the Legislature to change the law and strip away the governor’s traditional power to fill vacancies.

Democrats gleefully did so. At the final vote, the Boston Globe reported, “hooting and hollering broke out on the usually staid House floor,” as House Speaker Thomas Finneran smirked: “It’s a political deal. It’s very raw politics.”

Five years later, Democrats engineered more “raw politics” — again at Kennedy’s urging.

During his final illness, knowing his own seat would soon be vacant, Kennedy encouraged Massachusetts lawmakers to overturn the 2004 law, and restore the authority of the governor — Democrat Deval Patrick — to pick his successor. The Legislature readily complied. After Kennedy’s death, Patrick appointed an old Kennedy loyalist, Paul Kirk, to hold the seat until a special election could be held. And when Kerry left the Senate to become secretary of state in January 2013, Patrick likewise picked his successor — another Democratic stalwart, Mo Cowan.

But now that the governor’s office is once more occupied by a Republican, Democrats are itching to change the law yet again.

Domb didn’t bother to pretend that her proposal to force Baker to replace Warren with a Democrat had any motive other than sheer partisanship. She wanted to protect the “balance of power in the US Senate,” she said, and to protect the “rock stars” of the Massachusetts congressional delegation, who “all happen to be Democrats.”

Her amendment has been shelved for now, but everyone knows Democrats are ready to turn on a dime if Warren is tapped for Biden’s cabinet. “It’s a little early to get in front of that at the moment,” the House Ways and Means Committee chairman, Boston Democrat Aaron Michlewitz, serenely told Sate House reporters last week. But “it’s a conversation that we are all willing to have.”

No doubt about that. If Warren leaves the Senate, the Legislature will see to it that a Democrat replaces her. Changing laws for partisan advantage may be disreputable, but when has that ever troubled Beacon Hill?

(Jeff Jacoby is a columnist for The Boston Globe).