President Trump’s made-for-prime-time television announcement of Neil Gorsuch, the Federalist Society’s favorite, as his nominee for the Supreme Court launched what promises to be an expensive cage match between Senate Democrats and Republicans over his confirmation. Given the context and the stakes, Democrats have no choice but to fight furiously to prevent Trump from filling this seat with a justice far to the right of the mainstream.

Context matters. Democrats and the country must never forget that Mitch McConnell and his party of thieves stole this seat from President Obama in a craven exercise of partisan power. But for McConnell’s unprecedented refusal to perform his basic constitutional duty to give Merrick Garland a hearing and a fair vote, the Court would now have a progressive majority that would protect reproductive rights, the right to vote, labor unions, environmental and consumer regulations, and civil rights. Instead, we face the return of the Scalia Court, at best; a Court that leans hard right to protect employers and undermine labor, weaken the right to vote, block environmental protections, and water down civil-rights protections with an occasional saving intervention from the otherwise conservative Justice Kennedy.

Based on Gorsuch’s performance on the US Court of Appeals for the Tenth Circuit and his public statements, he can be expected to be at least as conservative as Scalia. Indeed, he repeatedly has expressed his reverence for Scalia. He is a strong originalist and textualist, whose methodology consistently leads him to ideologically conservative results.

Emboldened by the Garland experience and the frighteningly chaotic, incompetent, and authoritarian start to the Trump administration, Democrats sound as if they’ll shed their instinct to accommodate and greet this nomination with appropriate skepticism. Judiciary Committee Chairman Chuck Grassley doubtless will try to rush the nomination through his committee, as he did with attorney-general nominee Jeff Sessions. Democrats, however, can and must insist that a hearing wait until the nominee fully completes the committee questionnaire and provides every piece of information relevant to confirmation. At the hearing, prepared Democrats should have little trouble establishing that the nominee falls well outside the judicial mainstream.

It is likely Republicans will vote as a bloc to report the nomination favorably to the Senate floor. The requirement of 60 votes to break a filibuster, however, remains the rule for Supreme Court nominations. If Democrats can hold onto 41 of their 48 votes, they can postpone a final floor vote indefinitely. The challenge will be to convince some of the 10 Democratic senators facing reelection in 2018 in states Trump carried that their political fortunes rest with the full-throated opposition of an energized Democratic base to the rapidly unfolding Trump catastrophe.

The flouting of constitutional tradition in the refusal to honor Merrick Garland’s nomination demonstrates that Republicans will do whatever is necessary to fill this seat. They may exercise the “nuclear option” to eliminate the 60-vote threshold to shut off debate, as Democrats did for lower-court judges in the face of unremitting obstruction by Republicans. Some have counseled Democrats to back off to preserve the filibuster for a second Trump nominee, who might replace Anthony Kennedy or a more liberal justice. Such an appointment could lock in for a generation an even more solid conservative majority that would jeopardize fundamental precedents on abortion, same-sex marriage, affirmative action, and the death penalty. But Democrats should not succumb to speculation. It is also possible they may recapture a majority in the Senate in 2018, allowing them to stop any unacceptable nominee, or there may not be another vacancy during the Trump presidency. And, in any event, Republicans will eventually attempt to eliminate the 60-vote requirement rather than relinquish a seat.

The stakes are too high for accommodation. For example, the Court recently declined to hear a challenge to the Texas photo-ID law, which lower courts found disproportionately deterred minority voters in violation of the Voting Rights Act. But that case is now in its second stage of litigation and will come back to the Court, where a solid conservative majority will be able to reinstate the Texas law and others, damaging minority and, therefore, Democratic voting strength. Also, last term the Court split 4-4 in a case that would exempt non-union public employees from contributing a fair share to unions to cover the costs of collective bargaining. That issue would surely return to a Court with a conservative majority that would decide it against labor. The list goes on to include contraception, clean power, consumer protections, and other vital issues.

This fight has a larger political context. Democrats in the Senate finally seem to be receiving the powerful message from the grassroots—from the millions who have marched and organized against Trump—that they must resist Trump’s right-wing authoritarian capture of our institutions of government. They have belatedly shown spine in resisting some Trump cabinet nominees. The most effective means of protecting our institutions is to harness the energy of an increasingly alarmed electorate to win majorities in Congress in 2018. Those who don’t get out in front of the Trump resistance are in danger of being left behind. Opposition to filling the stolen Supreme Court seat with a man who has repeatedly professed his admiration for the radically conservative vision of justice espoused by Antonin Scalia is a necessary step.