From his perch on the dais on the opening day of Brett Kavanaugh’s confirmation hearing last week, veteran Sen. Patrick Leahy, D-Vt., lamented the state of the Senate Judiciary Committee.

“This is not the Senate Judiciary Committee that I first came to,” said Leahy, a former chairman of the committee who has voted on 19 Supreme Court nominees in his 44-year Senate career.

The Vermont Democrat went on to blast Republicans for withholding key documents from Kavanaugh’s time in the Bush White House, in what became a running line of attack from Democrats opposed to his confirmation.

“The Senate is not simply ‘phoning in’ our vetting obligation. We are discarding it,” Leahy said. “It is not only shameful. It is a sham.”

Leahy’s frustration laid bare the extreme partisanship surrounding Kavanaugh’s confirmation process.

But that partisanship surrounding Kavanaugh isn’t new. The modern politicization of the Supreme Court nomination process dates back to the mid-1970s, according to George Washington University political science professor Sarah Binder.

As Congress and presidential elections became increasingly hyper-partisan in recent decades, it was only a matter of time before the nominally apolitical Supreme Court followed suit, Binder said.

“We’ve seen this sort of rising polarization both in the House and the Senate [and] with the presidency,” Binder said. “So the fact that we now see similar partisan dynamics [with the Supreme Court] probably shouldn’t be very surprising. It’s just taken longer for the court to get there.”

In Kavanaugh’s case, the partisan fighting over his nomination continued Thursday, when the Judiciary Committee delayed its vote and rescheduled it for next week; the full Senate vote is expected at the end of the month. President Donald Trump nominated Kavanaugh, a federal judge on the D.C. Circuit Court of Appeals, in July.

The move Thursday to delay the committee vote came hours before Sen. Dianne Feinstein, D-Calif., the panel’s top Democrat, announced that she had referred information on Kavanaugh to federal investigators. The New York Times reported that the incident in question “involved possible sexual misconduct” when Kavanaugh was in high school.

Past confirmation votes underscore the growing partisan divide over Supreme Court nominees. In March 2017, the Senate confirmed Neil Gorsuch to the Supreme Court by a 54-45 vote. In contrast, the Senate confirmed the late Antonin Scalia, who Gorsuch replaced, by a 98-0 vote in 1986.

Scalia’s unanimous confirmation wasn’t a complete outlier. John Paul Stevens was confirmed 98-0 in 1975, and Sandra Day O’Connor joined the bench on a 99-0 vote in 1981. Retired Justices Anthony Kennedy — whom Kavanaugh would replace — and David Souter both received 90 or more votes. (There were closer votes during that period as well; Chief Justice William Rehnquist was confirmed 65-33 in 1986).

The last Supreme Court justice to receive at least 90 votes was Ruth Bader Ginsburg, who was confirmed 96-3 in 1993. The following year, the Senate voted 87-9 to conform Stephen Breyer.

But since then the margin has narrowed, though the final votes have swung back and forth. Chief Justice John Roberts, who was confirmed in 2005, was the last nominee to receive 70 or more votes. Kavanaugh is widely expected to garner about the same number of votes as Gorsuch last year.

Moreover, Supreme Court confirmation votes are increasingly falling along party lines, a consequence of heightened partisanship on Capitol Hill.

The last Supreme Court justice to receive at least 90 votes was Ruth Bader Ginsburg, who was confirmed 96-3 in 1993.

“It is a development of recent decades [that the Court] has become as partisan as it is now”, Michael Waldman, the president of the nonpartisan Brennan Center said. “We have gone from routinely having supermajorities for nominees in both parties to narrow-to-almost-party-line votes for Supreme Court justices.”

The Senate is partly responsible for the increasing partisanship. Senate Majority Leader Mitch McConnell’s refusal in 2016 to consider the nomination of Judge Merrick Garland, President Barack Obama’s pick to replace Scalia, infuriated Senate Democrats.

Under McConnell, Republicans also triggered the so-called “nuclear option,” a rules change that allowed the Senate to confirm Supreme Court nominees on a simple majority vote, instead of the traditional 60-vote threshold. Doing away with the filibuster paved the way for the type of near party-line vote that confirmed Gorsuch last year.

At the same time, the nominees presidents have picked in recent years have also been more ideological. Binder argued that was especially true of nominees appointed by Republican presidents.

In the past three decades, Supreme Court nominees picked by Democratic presidents have been “consistently pretty liberal,” she said. “But Republican justices appointed by Republican presidents over the last several decades have seemingly moved further to the right.”

Conservatives have lobbed the same criticism at Democrats and their Supreme Court nominees. But Binder argued the rightward drift by GOP presidents has been deliberate, and reveals the strength and organization of groups in the conservative legal community, like the Heritage Foundation and Federalist Society, which have pushed to get conservative judges on the bench.

The Federalist Society in particular has flexed its muscle under Trump. Leonard Leo, the vice president of the group, was a close advisor to the Trump campaign in 2016 and reportedly played a major role in crafting the short list of potential Supreme Court nominees to fill Scalia’s seat.

Gorsuch was on an expanded list of possible Supreme Court nominees the campaign released in September 2016. Kavanaugh did not make the lists put out before the election, but was included in a list of potential court picks the White House put out last year.

“Conservatives have taken the politics of judicial selection seriously,” Waldman said. “There’s no precedent in American history of the role the Federalist Society has played.”

The Federalist Society does not take a position on judicial nominees, according to the group’s website.

Josh Blackman, a professor at the South Texas College of Law, Houston and a member of the Federalist Society, noted that historically Supreme Court nominations have always been intertwined with the political battles of the day.

Throughout the 1800s, Supreme Court nominees were often approved or rejected by a small handful of votes, at a time when there were far fewer seats in the Senate. Votes like the one for William Smith (who was approved 23-18 in 1837), or Lucius Lamar (approved 32-28 in 1887) were common.

“It’s hard to pick a point in time where things got bad. But the Bork nomination is probably where things started going awry,” Blackman said, referring to Robert Bork, who was rejected by a 42-58 vote in 1986 and is the last Supreme Court nominee to be turned down by the Senate.

More recently, “the Garland situation poisoned the well further,” he said.

“I think it’s unfortunate. By any reasonable account Judge Kavanaugh is qualified” to serve on the Supreme Court, Blackman said. In another era, he would likely have been confirmed on a unanimous, or near-unanimous vote, he added.

“I think the new normal is straight party line votes, or something close to it,” he said.

Throughout his hearings, Kavanaugh stressed the importance of having an independent judiciary that’s insulated from partisan politics. He said he considered himself an independent judge, something backed up by numerous witnesses who testified on his behalf.

In the months since Trump nominated Kavanaugh, Republicans have argued that the D.C. Circuit Court of Appeals judge is well within the “mainstream” of legal thought. Opponents have said his appointment to the bench would shift the Supreme Court further to the right.

A more polarized Supreme Court — and more high-profile 5-4 rulings that fall along ideological lines — could further erode the court’s image as an impartial institution, Binder said.

“The danger is that Americans will start to see that the court as just another political actor to the extreme,” Binder said.

The court could be in danger of being ‘seen as another cable debate show with five conservatives and four liberals.’

Or as Waldman put it, the court could be in danger of being “seen as another cable debate show with five conservatives and four liberals.”

The partisan gridlock in the Senate has been on full display recently as vulnerable Democrats decide whether to support him or not. Three Democrats who voted to confirm Gorsuch last year are up for re-election in November in states that Trump won in 2016. But now, less than two months from Election Day, the politics surrounding Kavanaugh’s confirmation are even more complicated.

For vulnerable Democrats, a vote for Kavanaugh could help with voters who support Trump. But a recent CNN poll found only 38 percent of Americans believe Kavanaugh should be confirmed. Split by party identification, the poll found 63 percent of Democrats and 40 percent of Independents say the Senate should not vote to confirm Kavanaugh.

Despite the divisions Kavanaugh is widely expected to get confirmed. Whatever the final vote, the battle over his nomination has proved the system is breaking down, said Blackman, the law professor at the South Texas College of Law.

“The confirmation process is in a pretty poor place,” he said. “But I don’t see any way out of it given our current order.”