NAPLES, Fla.

LAST week, senators blocked a compromise measure that would have compelled unlicensed sellers at gun shows and online gun sellers to conduct background checks, despite polls that showed that 90 percent of the public supported the idea.

I’m a libertarian who played a role in reducing handgun restrictions in the nation’s capital. In 2008, in a landmark case I helped initiate, Heller v. District of Columbia, the Supreme Court declared for the first time that the Second Amendment protected an individual’s right to bear arms.

But the stonewalling of the background check proposal was a mistake, both politically and substantively. Following a series of tragic mass shootings, public opinion is overwhelmingly in favor of reasonable legislation restricting the ownership of guns by people who shouldn’t have them. There was also plenty in the proposal that gun-rights proponents like me could embrace.

The compromise — carefully negotiated by two moderate gun-rights supporters, Senators Joe Manchin III, Democrat of West Virginia, and Patrick J. Toomey, Republican of Pennsylvania — should be reintroduced in the Senate. I am convinced that, with some modifications, it could still be passed, because it would add reasonable protections for both gun owners and sellers.