In an interview last week, President-elect Donald Trump’s Chief of Staff and former Republican National Committee head Reince Priebus promised on NBC’s “Meet the Press” that the new administration would not implement a religious registry.

The idea of forcing certain groups of individuals to ‘register’ based on religion is a spinoff of the total ban on Muslims that Trump proposed during his campaign. In response to this proposal, a  number of Republican leaders – including soon-to-be Vice President Mike Pence – vehemently pushed back. Such a policy would be, in the words of Pence, “offensive and unconstitutional.”

Just days before Priebus’s rejection of the religious registry alternative, Representative Susan DelBene (D-WA) introduced H.R. 6382, the “No Religious Registry Act.” The bill prohibits the collection of information and the establishment or utilization of a registry for the purposes of classifying  individuals in the U.S. based on religious affiliation.

As of today, 49 Democrats have signed onto the bill. In light of Priebus’ guarantees, Republicans should also have no qualms about vocally supporting the legislation in droves.

Nonetheless, Priebus would not denounce the possibility of the resurgence of a more robust Muslim database. Although the difference between a religious registry and a Muslim database may seem insignificant, it is actually quite substantial.

Tracking Muslims is not a new concept in America. The National Security Entry-Exit Registration System (NSEERS) program instituted under George W. Bush’s Department of Justice after 9/11 required certain foreign nationals in the United States to submit fingerprints and photos, and to check-in at regular intervals for interviews. Integral to the legality of the program was to whom it applied: non-immigrant men over the age of 16 who came from countries on Bush’s list of terrorist-supporting countries.

Although the details of any future program will determine its ultimate legality, at first blush, it is likely not legally tenable to institute a similar program that targets all individuals in the United States for registration and interrogation solely due to their practice of a particular religion — a Constitutionally-protected First Amendment right.

In all likelihood, the elements of the registry and the means by which the United States learns who is a practicing member of a proscribed religion will violate — or at least unreasonably chill — the free exercise clause of the First Amendment.

Supporting the No Religious Registry Act is the first step Republicans must take to ensuring that any action taken in the name of national security remains legally defensible.