News reports had barely confirmed the passing of Justice Antonin Scalia when Senate Majority Leader Mitch McConnell announced that his chamber would neither offer its advice nor consent to any nomination made by President Obama to fill the suddenly vacant Supreme Court seat. The timing of McConnell’s proclamation may have been distasteful, but his effort to get in front of the coming confirmation battle was telling. By staking out an absolutist position – no hearings, no vote, no compromise – he was telegraphing how he cannot afford to have a Democrat make this pick. Court appointments in recent years have been contentious as a matter of course, but this one is different because it could fundamentally alter the structure of political competition, striking a lethal blow to conservative hopes for majority status in a new political alignment.

Not surprisingly, McConnell’s rejectionist approach rapidly became the de facto party position. Republican senators and leading contenders for the Republican presidential nomination lined up behind him to demand that the next president appoint Scalia’s replacement because, after all, it’s an election year and we have to wait for the people to speak before the president can act. While the implication that the people didn’t speak three years ago when they elected the current president surely plays well in partisan circles where questions about Obama’s legitimacy are not new, McConnell and company must have realized they were saying these things out loud where everyone could hear them. Why take such an extreme position and risk being painted as obstructionists during an election year when it was possible to sound accommodating, go through the motions of considering the president’s nominee, and then vote no? Because McConnell doesn’t want to personify this fight by placing a potentially sympathetic nominee in the spotlight or lose control of the nomination process by holding unpredictable hearings. Republicans control the senate calendar but that is the only card they hold, and everything is suddenly, unexpectedly on the line.

When movement conservatives were engaged in their decades-long march from obscurity in the 1950s to control of the Republican Party and the country decades later, they learned that if you want to change social conditions you have to control the courts, and if you want to control the courts you have to run the executive branch, where nominations are made. By forging a national coalition that could win presidential elections as early as 1968, they were able to nudge the federal court system to the right even though they wouldn’t take full control of congress until 1994. And although conservatives have been bitterly disappointed by recent Court rulings about policies like the Affordable Care Act and gay marriage, the Court has been the Republican Party’s most important ally on matters affecting how the political game is played. Up and down the ballot, Republicans benefit from the flow of dark money unleashed by Citizens United, voter ID laws that disproportionately disenfranchise Obama coalition voters, the weakening of the Voting Rights Act, and aggressively drawn congressional districts that provide a firewall against Democrats recapturing the House. All of these were held in place by the single vote that Justice Scalia took with him when he departed.

Republicans may be able to delay the appointment of an Obama nominee, but that is not a permanent fix. McConnell’s blocking action is meaningful only if Republicans can produce a presidential candidate capable of competing next fall. In the near term it is the necessary step that protects his party’s long-term ability to compete with Democrats in the wake of daunting demographic challenges and a base that’s at odds with the emerging electorate. Any number of things can derail McConnell’s strategy. Republican senators up for re-election in blue states could defect under political pressure. Public opinion could turn against Republicans, complicating their efforts to win the White House. But should the senate – now or next year – confirm a Democratic nominee with an activist bent who is skeptical of corporate personhood and holds liberal views of civil rights and equal protection, a newly constituted 5-4 progressive Court majority would begin to undermine the key legal and institutional advantages that are helping to keep Republicans afloat as their once-dominant coalition falls apart.

Until last weekend, a situation like this was purely hypothetical. You could have speculated (and I did) that a Democrat is likely to win the next election, after which an older conservative justice might decide he’d rather play golf than take his chances on a Republican comeback in 2020. But now it is real, and it’s going to make the acrimony of the last seven years look like summer camp.

This is the whole ballgame.