It has been almost six months since Supreme Court Justice Antonin Scalia died unexpectedly, and almost five months since President Obama nominated Merrick Garland, the widely respected and centrist chief judge of the federal appeals court in Washington, D.C., to succeed him.

Because of obstructionism by Senate Republicans, however, the Senate is no closer to holding a hearing on Garland’s nomination, much less voting on it. Meanwhile, the court has divided 4 to 4 in some cases, preventing a definitive resolution of important issues including the legality of Obama’s executive action temporarily granting deportation relief and work permits to 4 million immigrants.

Within hours of Scalia’s death, Senate Majority Leader Mitch McConnell announced that he wouldn’t act on a new nomination by invoking — or, rather, inventing — the principle that a Supreme Court vacancy that occurs in a presidential election year can’t be filled “until we have a new president.” At the Republican National Convention, McConnell put it more bluntly: “I made (a) pledge that Obama would not fill this seat.” If he follows through on that promise, it would leave the court hamstrung by its 4-4 split, possibly through its entire 2016-17 term.

This is shameless partisanship, and it could also be self-defeating. As Obama has warned, continued obstructionism on the Garland nomination could lead to “an endless cycle of more tit for tat (that would) make it increasingly impossible for any president, Democrat or Republican, to carry out their constitutional function.” That’s a message the president and Senate Democrats need to revive when the Senate returns to work after Labor Day.

Given the Republicans’ recalcitrance so far, such pressure might seem pointless. But where principle might not move Senate Republicans to do the right thing, politics might. With Donald Trump lagging in the polls, McConnell and his colleagues are probably asking themselves whether confirming Garland in this Congress wouldn’t be preferable to waiting to see who might be nominated next year by a President Hillary Clinton.

That course would be especially attractive if Clinton won and Garland’s nomination was considered during a postelection lame-duck session. Although Clinton hasn’t said she would renominate Garland if she was elected, she has said “the president is on the right side of both the Constitution and history” in pressing the Senate to act on the nomination. Over the weekend, Democratic vice presidential nominee Sen. Tim Kaine replied “absolutely” when he was asked whether the Garland nomination should be taken up in the lame-duck session.

If the Senate takes its responsibility to the Constitution seriously, it will act even sooner than that.

— The Los Angeles Times, Aug. 9, 2016