Within days of taking office, Republican President Donald Trump announced his first Supreme Court nominee: the conservative Judge Neil Gorsuch.
Democrats immediately cried foul.
The seat on the nine-member Supreme Court had opened about a year earlier, but Senate Republicans had blocked President Barack Obama's choice while making the unprecedented argument that no nominee should be considered during an election year. The American people would decide the next Supreme Court justice, the GOP argued, via the 2016 presidential election.
The gamble, led by Majority Leader Mitch McConnell, paid off, but getting Trump's pick onto the nation's highest court would require a similarly historic and aggressive tactic: a "nuclear option" change to Senate rules.
As the chamber prepares for another contentious showdown over retiring Justice Anthony Kennedy's successor, here's a look back at how the Senate has altered the rules in recent years when it comes to confirming judges.
Eliminating the filibuster for presidential nominees
In 2013, Senate Democrats — then in the majority — triggered the nuclear option for the first time.
Frustrated with what they considered the relentless Republican obstruction of Obama's appointments, Democrats led by Senate Majority Leader Harry Reid of Nevada, changed the rules so that lower court and Cabinet nominees could be confirmed with a simple majority, rather than the typical 60-vote threshold.
McConnell railed against the change at the time, though the 60-vote threshold still applied to high court nominees.
However, when it came time to confirm Gorsuch in 2017, near-unified Democratic opposition and the GOP's own slim majority of 51 Republican senators made getting to a 60-vote supermajority impossible.
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Last April, McConnell triggered a rules change, clearing the way for Gorsuch to be confirmed with a simple majority. The use of the nuclear option for Supreme Court nominees was dramatic for a body like the Senate, which operates on tradition and precedent.
Remember Merrick Garland?
In February 2016, days after the conservative Supreme Court Justice Antonin Scalia died, Republicans made an unprecedented declaration: The Senate would not hear or confirm any nominee to fill the unexpected vacancy until the country had elected a new president in November.
Don't even try nominating anyone, McConnell told Obama, the Constitution requires "the advice and consent of the Senate."
"We intend to exercise the constitutional power granted the Senate under Article II, Section 2 to ensure the American people are not deprived of the opportunity to engage in a full and robust debate over the type of jurist they wish to decide some of the most critical issues of our time," Republican members of the Senate Judiciary Committee wrote in a letter, claiming the move was "born of a necessity to protect the will of the American people."
Obama nominated Judge Merrick Garland anyway. His nomination lingered for eight months — Garland passed the time with puzzles and volunteering, it was later reported — before Republican Donald Trump won the presidency and dashed any leftover hopes that Garland might one day take a seat on the nation's highest court.
Supreme Court nominations have long been contentious — past rulings were poured over, qualifications dissected, witnesses interviewed — but Garland was the first nominee in decades to be denied any kind of consideration by the Senate.
Fact checking the "Biden rule"
To justify the decision to break from Supreme Court nomination precedent, Republicans pointed to a similar appeal made by none other than Obama's own vice president, Joe Biden, decades earlier.
"It is my view that if a Supreme Court justice resigns tomorrow or within the next several weeks, or resigns at the end of the summer, President [George H.W.] Bush should consider following the practice of a majority of his predecessors and not — and not — name a nominee until after the November election is completed," said Biden, then the chairman of the Senate Judiciary Committee in June 1992.
But Biden said his remarks — which centered on a hypothetical Supreme Court vacancy during an election year, in which the branches of government were controlled by different parties — were taken out of context. Indeed, Biden's floor speech goes on to promise Bush his support if he were to choose a moderate.
"I believe that so long as the public continues to split its confidence between the branches, compromise is the responsible course for both the White House and for the Senate,” he concluded in that floor speech. “If the president consults and cooperates with the Senate, or moderates his selections absent consultation, then his nominees may enjoy my support as did Justices Kennedy and Souter. But if he does not — as is the president’s right — then I will oppose his future nominees, as is my right."
Obama took Biden’s decades-old advice with the nomination of Garland, a centrist judge so well-liked there were no complaints about his qualifications or judicial philosophy, only the timing of his nomination.
"He was in his early to mid-60s, so it wasn’t like they nominated somebody who was 48 years old who would be on the court for 30 years. Obama did that as a gesture of conciliation — it didn’t do anybody any good at all," George Washington University Law Associate Dean Alan Morrison told NBC News.
Can Democrats now create their own blockade?
The impending retirement of Justice Anthony Kennedy has Democrats singing McConnell's old tune.
"Our Republican colleagues in the Senate should follow the rule they set in 2016 — not to consider a Supreme Court justice in an election year," Minority Leader Sen. Chuck Schumer, D-N.Y., said on Wednesday afternoon.
But with just 51 Republicans in the Senate — and Sen. John McCain, R-Ariz., unwell and out of Washington — a cohesive Republican caucus could limit Democrats' influence.
If all the Republican senators — minus McCain — vote to confirm while the Democrats and independents vote against a nominee, Vice President Mike Pence could break the tie and confirm Kennedy's successor. But losing one Republican vote, without winning any Democratic ones, would halt the confirmation.
"If they’re an odd number, the vice president can’t vote to create a tie," Morrison said. The vice president can only break a tie when the votes are equal, according to the Constitution.
Still, he added, there is just one sure bet: "It's certain to be contentious."