On February 13, Justice Antonin Scalia died at a hunting lodge in Texas. That same day, Senate majority leader Mitch McConnell made this announcement: “The American people should have a voice in the selection of their next Supreme Court justice. Therefore, this vacancy should not be filled until we have a new president."

McConnell's statement was not quite off the cuff but close. The Senate had just begun a weeklong recess, making it impossible to get in touch with the other Republican senators and to listen, in McConnell's words, to their "53 different opinions." He acted.

His decision was lambasted by Democrats and the mainstream media as rash and a political mistake. He was accused of disobeying his constitutional duty to hold Senate hearings and then a vote on whomever President Obama nominated to fill the vacancy. By refusing, McConnell was told he would hurt Republican prospects in the 2016 election. There would be a public backlash. And so on.

The next week, McConnell took his case to his Senate GOP colleagues at their weekly lunch. By then, he and his staff had boned up on the history of nominees in the final year of a president's term. "The precedents were on our side," McConnell says. Even Democrats—Joe Biden, Harry Reid, Chuck Schumer—had dismissed lame-duck nominations as unacceptable.

"I'm not a dictator," McConnell says. "I had to convince my colleagues." At the lunch, only two Republican senators said they favor hearings. Today, those two are still the only dissenters.

Three months after his announcement, McConnell is vindicated. He not only thwarted the president and Democrats, he averted a potential catastrophe for Republicans if a popular Obama nomination had gone forward, splitting the party in an already divisive election year. Instead, "it's been a completely unifying process," McConnell told me.

The success of McConnell's strategy hasn't been widely acknowledged. Senate Democrats are reeling from a series of tactical blunders. Senate minority leader Harry Reid attacked Charles Grassley, the chairman of the judiciary committee, more than a dozen times for not scheduling hearings for Obama's nominee, Merrick Garland. The speeches were rants, typical for Reid.

Democrats tried to embarrass vulnerable Republican senators with what they called a "9-9-9" plan: nine senators in nine states to confirm a ninth Supreme Court justice. It bombed. Now Obama is insisting the Senate has a mandate to vote on his nominee. Actually, there is no such mandate.

Oddly enough, two scholars at the center-left Brookings Institution, John Hudak and Molly E. Reynolds, have studied McConnell's options and given him high marks. "Mitch McConnell didn't make a mistake," they wrote.

"The charges that he blundered . . . are foolish. In fact, McConnell's strategy, and the speed with which he worked through the possibilities to come to the 'right' conclusion, was not a political misstep. Instead, it is the mark of a political master."

That's not all. "With an opportunity to maintain or even enhance conservative enthusiasm—particularly in a year in which the Republican Party appears to be on a confusing soul-searching mission—McConnell jumped at it," Hudak and Reynolds said. Republicans of all ideological stripes are on board.

His blockade of Obama's nominee "will keep safe [Republican] seats safe . . . ensure that At-Risk Senators remain safe . . . [and] provide McConnell a chance to stem some of the almost certain losses among Vulnerable Senators," the scholars wrote.

McConnell has long been regarded as a clever politician who skillfully keeps Senate Republicans in agreement. This time, he also showed remarkable foresight. He saved Republicans from having to deal with an attractive nominee, possibly a gay or an African-American or a Hispanic. McConnell's decision was based on the principle that a president on the way out the door shouldn't put a new justice on the Supreme Court. "It doesn't make any difference how qualified the nominee is," McConnell says. His motto is "it's about the principle, not the person."

Once the confirmation process began, it would be difficult to control. And Obama and Democrats would attack opposition by Republicans as meanspirited, cynical, mindlessly partisan, and bigoted. That's the normal pitch of Democrats. McConnell spared Republicans these attacks.

Democrats cite polls in their demand that the Senate take up Garland. But polls don't help their case much. They show three things: A majority favor hearings and a vote, the nominee issue ranks low in the minds of most voters, and only a distinct minority thinks of it as an issue on which to base their vote.

McConnell's reputation as a firm leader played a part in the success of his strategy. He may have scared off stronger nominees who figured McConnell wouldn't flinch. They didn't want to jeopardize their chance of being nominated by Hillary Clinton if she's elected president. True, Garland was backed by liberal interest groups, but he didn't stir mass enthusiasm on the left—far from it. Any hope of his being confirmed is gone.

Democrats bet that Grassley would be the GOP's weak link. They were wrong. Last week, they brought five Iowans and supposed Grassley backers to Washington to express their dismay with him. But two were Democratic donors and only one said Grassley's refusal to hold hearings might prompt a vote against him. The stunt flopped. Though he's running for his seventh term, Grassley was unfazed by a harsh (but silly) editorial in the Des Moines Register.

In March, McConnell and Grassley met at the White House with Obama, Biden, and Reid. McConnell needled them about their hypocrisy in insisting on a vote on Garland. "Only two of us here never filibustered a Supreme Court nomination," McConnell noted. Obama, Biden, and Reid filibustered the nomination of Sam Alito in 2006. They lost then too.

Fred Barnes is an executive editor at The Weekly Standard .