Early this morning, Supreme Court Justice Antonin Scalia, a father of nine, passed away in Marfa, Texas. Scalia was one of two originalists—that is, those who believe that laws mean what they were intended to mean—on the court (the other, of course, being Clarence Thomas). His approachable writing style made esoteric questions of law interesting even to laymen, and his ability as a jurist will leave a lasting mark on the court. Other justices, although not themselves originalists, were gradually pushed toward more rigorous scholarship by Scalia’s fiery voice in the opposition.

Scalia was, however, very definitely in the minority throughout his time on the court. Even when he agreed with his colleagues’ decision, he often wrote concurring opinions to explain his own reasoning, which differed markedly from his colleagues’. Outnumbered, he described his successes as “d–n few” and lamented that “day by day, case by case, the Supreme Court is busy designing a Constitution for a country I do not recognize.”

Scalia was one of only a handful of jurists who held to his view of originalism. They are outnumbered by far by those who believe that the laws in general, and the Constitution in particular, do not necessarily mean what they were intended to mean, and that the Supreme Court is the only body with the ultimate authority to determine what they really did mean. Scalia’s death leaves only one originalist on the Supreme Court. If the trend he observed in Supreme Court decisions is to be reversed, his successor must be one of this minority dedicated to a rational interpretation of the Constitution.

President Obama will not appoint a successor who is even remotely sympathetic to Scalia’s principles. Indeed, if Obama’s previous nominations are any indication, should he be successful in appointing Scalia’s successor, it would be one of the biggest ideological shifts in the history of the court, from a staunch originalist to an advocate of a living constitution, a constitution that changes to mean whatever the justice wants it to at the moment. It is imperative, then, that the Senate refuse to confirm any nominee who does not adhere to an originalist view of the Constitution. Anything else would create a shift away from the rule of law, in which the text of laws is meaningful, to a government by the whim of five justices.

Such a refusal would likely mean that the seat remains vacant at least until Obama leaves office nearly a year from now. This would be far from unprecedented—the last time a vacancy opened during an election year, the nominee was filibustered and withdrawn, and the longest-lasting Supreme Court vacancy lasted more than a year when Congress refused to confirm the lame-duck President Tyler’s nominations—and it is absolutely necessary. The two originalists on the court usually allied with Justices Alito and Roberts, who, although not strictly originalists, had some regard for the meaning of the text, to oppose four advocates of a living constitution, with the philosophically confused Justice Kennedy providing the deciding ninth vote. Shifting one of the most strident and brilliant textualist voices to that of a full-throated liberal would nearly guarantee defeat for advocates of the original intent or original meaning in every case brought before the Supreme Court. Republican Senators who haven’t stood on their hind legs and fought in their entire careers need to now, or risk potentially irreparable damage in the period before the next president will hopefully appoint a more rational justice (which relies, of course, on the assumption that the Republicans don’t nominate Trump, who has said that his pro-abortion sister would be “one of the best” Supreme Court justices, and that the Republican nominee wins).

If ever there was a time for Republicans in the Senate to stand their ground, this is it. Republicans have already vowed to block Obama’s nominees, but conservatives need to be willing to support those holding the line and hold those who flinch from the confrontation accountable. For twelve months—the second-longest Supreme Court vacancy in history—the Senate will be a battlefield, but if our country is to remain one that Justice Scalia would recognize, we must win.