After seven years of trying and failing to significantly chip away at the Second Amendment, President Obama may have stumbled into the opportunity he’s been waiting for. The death of Supreme Court Justice Antonin Scalia, whose conservative ruling in District of Columbia v. Heller is the definitive modern interpretation of that crucial right, leaves open the possibility that Obama will replace him with a liberal judge.

“We are one justice away from a Supreme Court that would harm our Second Amendment rights,” the National Rifle Association said on social media.

In the Heller case, the Supreme Court issued its first comprehensive ruling on the Second Amendment in 70 years. In a 5-4 ruling along partisan lines, the Court – led by Scalia – found that the right to bear arms was not just limited to the formation of a militia.

“Undoubtedly some think that the Second Amendment is outmoded in a society where our standing army is the pride of our nation, where well-trained police forces provide personal security, and where gun violence is a serious problem. That is perhaps debatable, but what is not debatable is that it is not the role of this Court to pronounce the Second Amendment extinct,” Scalia wrote in the landmark assent.

The decision did not throw the doors open to unlimited firearm rights – even Scalia acknowledged that the Second Amendment, like every other right, came with reasonable restrictions – but it clarified the individual right to bear arms. It struck down D.C.’s handgun ban, and it prevented other cities from thwarting the constitutional rights of their citizens. Skirmishes continue, but Americans need not worry about a widespread, all-encompassing firearm ban as long as Heller remains the court’s final word on the subject.

Unfortunately, the “individual” interpretation of the Second Amendment is fiercely opposed by liberal jurists. They not only argue that the right to bear arms is outdated, they claim that the founding fathers never intended it to apply to individual citizens in the first place. As the NRA pointed out, it would only take one more liberal Justice to undo the Heller decision and make the Second Amendment forever obsolete.

That’s what’s at stake in this election, and Republicans had better get very clear on it as they move forward. It’s not just Scalia. Several other Justices are getting up there in age, meaning the next president could have the power to significantly change the shape of the Court. With our fundamental, original rights on the table, voters cannot afford to put a Democrat in the White House.