Of course, it’s not only Supreme Court picks that count. Lower-court appointments matter enormously as well, a reality of which the Senate majority leader, Mitch McConnell, is exquisitely aware, as demonstrated by his efforts to ram through circuit court nominations at a dizzying clip. Thanks to Mr. McConnell’s labors, Mr. Trump installed a record number of federal appeals judges in his first year. This bench packing will be one of the Republican lawmakers’ prime talking points on the campaign trail this fall.

The trillion-dollar question is whether Democrats can also use this battle to turn out their voters. This is not a given. If progressives wind up feeling as though their team didn’t fight fiercely enough against Mr. Trump’s nominee, they could be less inspired to show up at the polls. But even if Senate Democrats pull out all the stops, the political reality is that Republicans have been far more effective than Democrats at galvanizing their base around the judiciary.

Certainly this was the case in 2016: Whatever impact the former F.B.I. director James Comey or Russian hackers had on the race, Mr. Trump owes a big chunk of his win to Mr. McConnell for shamelessly refusing to fill Justice Antonin Scalia’s empty seat until after the election. Even conservatives turned off by Mr. Trump’s sexual creepiness could be rallied around the prospect of claiming that seat. In his endorsement of Mr. Trump, Senator Ted Cruz of Texas listed the Supreme Court as his top reason, warning supporters, “We are only one justice away from losing our most basic rights, and the next president will appoint as many as four new justices.” Even the maverick, country-before-party Senator John McCain of Arizona vowed that, if Hillary Clinton won the presidency, a Republican-controlled Senate would block any nominee that she put forward. Despite Democratic outrage over the blockading of President Barack Obama’s court pick, more Trump supporters than Clinton supporters cited the appointment of justices as “very important” to their vote.

This is not to suggest that Democrats don’t care about the judiciary. The issue just hasn’t resonated as widely and viscerally with their base as it has with Republicans, where the threat of judicial activism has become a reliable, enduring motivator. At least since early in the Obama era, Democratic voters have held a generally more positive view of the Supreme Court than their Republican counterparts. Survey data also show that Democrats, at least until recently, have tended to see the court more as what it is supposed to be, a neutral, independent arbiter. Republicans, by contrast, have been more likely to see it as a hostile force to be overcome. And, of course, the dream of one day overturning Roe v. Wade helps keep social conservatives fixated on remaking the judiciary.

The rise of Mr. Trump has created an imperative to change all this. Even before Justice Anthony Kennedy announced his retirement last week, nervous progressives had started working to close the urgency gap. This spring, the Committee for a Fair Judiciary, which advocates progressive judicial values, beefed up its lobbying shop. Around the same time, a gaggle of Democratic operatives formed a nonprofit group, Demand Justice, aimed at energizing voters around the courts. Demand Justice hopes to change the current political dynamic, in which Democrats and progressive interest groups typically mobilize to battle a specific court nominee, after which their energy and attention quickly dissipate. Through a combination of education and activism, the group wants to make judicial appointments a core electoral concern for progressive voters and a standard talking point for Democratic politicians. Among other efforts, they plan to set up a database that enables the public to track which Democratic senators vote for which jurists at all levels, making it easier to hold lawmakers accountable at election time. Yes, that seems like a pretty obvious and basic tool — and the fact that it doesn’t already exist speaks volumes about Democrats’ failure to draw attention to the radicalization of the judiciary.