President Barack Obama's nomination of Merrick Garland, the widely respected centrist chief judge of the U.S. Court of Appeals for the District of Columbia, may be regarded as an apolitical choice — if only because the former federal prosecutor is hardly the dream pick of his party's progressive wing. But in reality, the political implications are substantial: Should Republicans fulfill their threat to not even hold hearings on the nominee, they demonstrate the party's true Achilles heel, an inability to compromise or put the nation's interests ahead of their own.

In many ways, it is a parallel to the presidential nomination process where Donald Trump leads a narrowing field of what, in more reasonable times, might be regarded as social misfits. The disdain of Mr. Trump and Sen. Ted Cruz for caution, for reason, for political negotiation or even tolerance of contrary opinion is well-documented. After so much congressional dysfunction, the right has fashioned a narrative that the real cause of political gridlock in Washington is an unwillingness of the Republican “establishment” to embrace extremism — as if bluster and willfulness ever softened opposition.

What are the consequences of ignoring Judge Garland from now until the next president is sworn into office 10 months from now? For starters, it could hand control of the Senate over to the Democrats. Make no mistake, no previous Supreme Court nominee has been threatened with such ill-considered treatment, not with 311 days left in a president's term. Justice Anthony Kennedy was confirmed in 1988 just 84 days after he was nominated during the last year of Ronald Reagan's second term. Polls show a majority of Americans want the Senate to act on Mr. Obama's nominee even before knowing who that would be. The adverse implications for the handful of Republican senators running in Democratic-leaning states are likely to be substantial.

Judge Garland is certain to come under attack whether he gets a hearing or not, but his credentials are solid, and his praises have been sung in the past by people like Chief Justice John Roberts and Sen. Orrin Hatch. So what does blocking him accomplish? Will it prove to Trump supporters that incumbent GOP senators are just as extreme as any outsider? Sorry, but no. From Jeb Bush to Sen. Marco Rubio, the most recent casualty of the party's fractious politics, the newly converted are viewed with distrust by the far right. Nor is allowing a hearing a decision that will hurt incumbents in a general election — although it might help some.

Here's another mistake Republican senators are making. They are buying into the argument that whoever replaces the late Justice Antonin Scalia will redefine the direction of the nation's highest court for years to come. As Justice Scalia might say, that's pure applesauce. In reality, the current court is stocked with more seniors nearing retirement than the early-bird dinner at Bob Evans. The next president might find himself or herself replacing Justice Kennedy (79 years old), Justice Ruth Bader Ginsburg (83), and Judge Stephen Breyer (77). Holding up Mr. Scalia's successor actually works against the goal of a conservative court by hurting the party's credibility with independents and potential crossover Democrats who will choose the next president.

But perhaps worst of all, this kind of naked partisanship will only invite reciprocity. Democrats may decide that if the final full year of a president's term is now regarded as lame-duck and stripped of appointment authority, perhaps the same should go for the final two of the next Republican president. When did “advise and consent” turn into hostage-taking? And if a Supreme Court nominee can be treated this shabbily, why not extend extremist politics to the rest of the judiciary or to Cabinet choices? Where does the usurpation of constitutional authority end?

The public rightfully expects President Obama to do his job. In nominating Merrick Garland he has not only chosen a supremely qualified jurist for the nation's highest court but he has demonstrated a willingness to temper his own politics by selecting a 63-year-old moderate who oversaw the successful investigation into the Oklahoma City bombing attack. Now the public expects the same performance from the Senate. That Republicans might not allow such a respected individual the courtesy of a hearing, let alone a vote, speaks volumes. It will remind voters that the GOP is not just the “Party of No,” it is the party of “Nobody Works.”