Washington Post reporter Robert Barnes explains where the Supreme Court stands after the death of Justice Antonin Scalia and how the vacant seat will impact the presidential election. (Whitney Leaming/The Washington Post)

The rancorous debate over picking a replacement for Justice Antonin Scalia reflects in many ways a growing public skepticism toward the U.S. Supreme Court itself, as its image has evolved from impartial arbiter of the laws to yet another politicized institution.

The nation’s highest court is not immune from the disillusionment that Americans feel toward all their institutions of government. Increasingly, the assumption seems to be that certain political outcomes are to be expected — and sometimes, even demanded — from the justices.

And now, the judiciary’s ostensible insulation from politics is wearing even thinner. With a vacancy that could shift the ideological balance of the court, Republicans are insisting that voters make a decision on who the next president will be, before anyone gets to make one on who the next justice will be.

“The American people should have a voice in the selection of their next Supreme Court Justice,” Senate Majority Leader Mitch McConnell (R-Ky.) said in a statement. “Therefore, this vacancy should not be filled until we have a new President.”

That, of course, is not strictly how the Constitution set things up when it gave the president a four-year term and set out the process for filling a vacancy on the court.

At a town hall in Elko, Nev., Democratic presidential candidate Hillary Clinton slammed Republicans' threats that they would block consideration of a Supreme Court nomination from President Obama. (Reuters)

In part, the Republicans’ determination to block President Obama’s chance at a nomination that could leave a lasting mark on the court reflects their fury over how its current conservative majority has allowed same-sex marriage to become the law of the land and has refused to gut the health-care law that is Obama’s signature domestic achievement.

The court issues “a lot of opinions where, if I were in the legislature, I certainly wouldn’t have voted for the program that was under review,” Chief Justice John G. Roberts Jr. said earlier this month. “I don’t necessarily agree with the substance of every piece of legislation simply because I determine it’s within the Constitution for Congress” to enact it.

However, that separation of roles is often lost in the political furor that surrounds the court’s decisions.

“To the extent that politicians and political parties decide to use the court as a political football, it is difficult for the justices to get out of the game,” said Tom Goldstein, an experienced Supreme Court litigator who has gained a following outside the courtroom through his widely read SCOTUSblog.

It is not an entirely surprising development, given the polarization of the country. The court finds itself “in the same hothouse that all our politics is in now,” said Ron Klain, who as a top aide in the Clinton White House led the effort to get Ruth Bader Ginsburg confirmed to the court. But Klain noted that as far back as the 1830s, Alexis de Tocqueville observed, “Scarcely any political question arises in the United States that is not resolved, sooner or later, into a judicial question.”

Even before Scalia’s death, the makeup of the court was becoming a hotly debated issue in the 2016 election.

Presidential candidates are often asked about how they would go about picking their nominees to the court. In the past, they have usually described the kind of judicial philosophy they are seeking or named past justices who might be models for the ones they would select.

It has been considered bad form for presidents to explicitly choose their judicial nominees based on specific issues — “litmus tests” that would constrain the justices’ independence.

Yet this year, both of the Democratic contenders have committed to doing precisely that.

Sen. Bernie Sanders (I-Vt.) has declared that he will not appoint anyone who does not promise to vote to overturn the court’s 2010 Citizens United decision that opened the floodgates of unregulated money in politics.

When former secretary of state Hillary Clinton was asked at a presidential forum earlier this month whether abortion would be a litmus test for her appointments, she replied: “I do have a litmus test. I have a bunch of litmus tests.” Among others, she said, would be preserving the Voting Rights Act, overturning Citizens United and preserving same-sex marriage.

In the wake of the court’s decision last June legalizing same-sex marriage, GOP contender Sen. Ted Cruz (R-Tex.) accused the justices of taking a “long descent into lawlessness.” He proposed a constitutional amendment that would subject the court to periodic elections — in effect, turning the justices into politicians.

Americans still hold the judicial branch in higher regard than they do the executive and legislative ones, but their confidence in it has dropped sharply in recent years.

A Pew Research Center poll last July found public disapproval of the court at a 30-year peak of 43 percent, following major rulings upholding the Affordable Care Act and legalizing same-sex marriage.

As with so many other things, Americans are polarized in how they see the court: In the Pew survey, just 33 percent of Republicans said they had a favorable opinion of the court, a 17 percentage­-point drop in four months. Over that same period, Democratic approval turned sharply upward, reaching 62 percent, up eight percentage points.

Regardless of party, few believed the court was making its judgments strictly according to the law. Seven in 10 of the respondents said that in deciding cases, the justices “are often influenced by their own political views.”

The tension goes back at least as far as the 1950s, when the court under Chief Justice Earl Warren — who came from a political background, having been governor of California — began to move beyond its traditional role and become an instrument of social change.

As the justices aggressively expanded civil rights and civil liberties, “Impeach Earl Warren” billboards appeared on roadsides throughout the South.

Another watershed came with the court’s decision in Bush v. Gore, when it stepped in to decide the outcome of the cliffhanger 2000 presidential election.

More than a dozen years later, retired justice Sandra Day O’Connor reflected that it probably had been a mistake for the court to take the case on which she had been a deciding vote.

“Probably the Supreme Court added to the problem at the end of the day,” she told the Chicago Tribune editorial board. It “stirred up the public,” O’Connor added, and “gave the court a less-than-perfect reputation.”

Scott Clement contributed to this report.