President-elect Donald Trump will soon announce his nominee to replace Antonin Scalia on the Supreme Court. Once he does, we’ll know within just a few hours whether there is any chance that the Senate will reject his choice. That’s because the politics of Supreme Court appointments operates at the speed of the modern news media, not at the stately pace of the Justices’ deliberations.

Two examples—one recent, one practically ancient—prove the point. About an hour after the announcement of Scalia’s death, on February 13th of last year, Senator Mitch McConnell, the Republican Majority Leader, said that the seat would be held open for the next President to fill. Even though there were more than eleven months remaining in President Obama’s term, McConnell said the Senate would neither convene hearings nor allow a vote on anyone Obama nominated, no matter how well qualified. McConnell stuck to that plan, and Judge Merrick Garland, Obama’s admirable, otherwise uncontroversial choice, spent months in demeaning limbo as his chances for promotion withered.

On July 1, 1987, President Ronald Reagan nominated Robert Bork to the Court, and moments later Senator Edward Kennedy took to the Senate floor with a scathing denunciation of that choice. In perhaps the most notable floor speech Ted Kennedy gave during his long career in the Senate, he said, “Robert Bork’s America is a land in which women would be forced into back-alley abortions, blacks would sit at segregated lunch counters, rogue police could break down citizens’ doors in midnight raids, school children could not be taught about evolution, writers and artists could be censored at the whim of the government.” Bork, unlike Garland, did get the chance to make his case at a confirmation hearing, but he never shed Kennedy’s portrayal of him as an extremist. The senator’s speech had mobilized a broad constituency against the nominee, and the Senate ultimately voted him down, by fifty-eight to forty-two.

Both McConnell’s decree and Kennedy’s speech were widely criticized at the time. McConnell was denounced for violating the Senate’s constitutional duty to review a President’s nomination to the Court; Kennedy was excoriated for distorting the record of a distinguished scholar and judge. McConnell and Kennedy, who were political opposites on the issues, responded to the charges in the same way: neither cared. They both recognized the importance of the Supreme Court to the issues that mattered most to them, and they believed that a few harsh words were a small price to pay for the chance to steer the Court in their preferred direction.

McConnell and Kennedy understood something else: speed matters, especially when it comes to Supreme Court nominations. Most Presidents’ choices for the Supreme Court are confirmed, usually without a great deal of controversy. Breaking that pattern requires a major political undertaking. Even back in 1987, Kennedy knew that the conventional wisdom in Washington congealed quickly. If Bork, a judge on the D.C. Circuit and a former Solicitor General and a professor at Yale Law School, was seen as a shoo-in, there would be little chance to build a case against him. Likewise, McConnell knew that he might well lose a debate about the qualifications of the person Obama named to the Court. (Indeed, Garland’s pedigree, which includes two decades on the D.C. Circuit, is impeccable.) So McConnell, with his precipitous vow of no confirmation of anyone, turned the debate away from the merits of any individual to a controversy about the responsibilities of the Senate during an election year. That kind of conversation was sufficiently abstract to avoid generating wide political interest, and, as it turned out, Garland’s nomination was largely forgotten during last year’s campaign.

There is, of course, an even bigger factor in determining whether any nominee is confirmed. When the President’s party controls the Senate (as is now the case), it’s extremely difficult to stop any nomination. The last Republican nominee to fail in a G.O.P. Senate was George W. Bush’s choice of Harriet Miers, in 2005; the last Democratic choice to go down in similar circumstances was Lyndon Johnson’s friend Abe Fortas, whom he nominated as Chief Justice, in 1968. Kennedy had a Democratic-controlled Senate during his crusade against Bork, and McConnell led a majority against Garland, too. But McConnell’s current advantage is modest—just fifty-two seats—and though he has likely allies in Democrats who serve in Republican-leaning states, no confirmation is assured at this point.

Still, Democrats will have to make a fast decision after Trump names his choice. (If they’re smart, they’re making up their minds about various candidates right now.) If they greet Trump’s nomination with politely stern vows of serious consideration and rigorous questioning at a hearing, confirmation will be nearly a certainty. If, instead, the senators break out the incendiary rhetoric of their late colleague from Massachusetts, then the new President may have a fight on his hands. In either case, we’ll know the outcome long before the confirmation votes are counted on the Senate floor.