Two congressmen, Rep. Dana Rohrabacher, R-California, and Rep. Earl Blumenauer, D-Oregon, sent a letter on Wednesday co-signed by 64 of their peers to House and Senate leadership and called for an extended protection of medical cannabis states.

The letter, addressed to Senate majority leader Mitch McConnell, Democratic Sen. Charles Schumer, House Speaker Paul Ryan and Democratic leader Rep. Nancy Pelosi, urged them to extend the Rohrabacher-Blumenauer provision which “has successfully protected patients, providers, and businesses against federal prosecution, so long as they act within the confines of their state’s medical marijuana laws.”

The amendment has been in place since Dec. 2014 and prevents the Justice of Department from “implementing their own State laws that authorize the use, distribution, possession or cultivation of medical marijuana.”

The bill was signed by five of Colorado’s seven House representatives: Republicans Ken Buck and Mike Coffman; and Democrats Diana DeGette, Ed Perlmutter and Jared Polis. Republicans Scott Tipton and Doug Lamborn did not sign it.

The letter included 46 states as well as two U.S. territories and the District of Columbia, which have enacted some form of legalization of medical cannabis.

Earlier this year, Attorney General Jeff Sessions asked congressional leaders to undo federal cannabis protections and argued the amendment would “inhibit the Justice Department’s authority to enforce the Controlled Substances Act.”

In May, the Senate Appropriations Committee had approved the amendment to protect state medical cannabis programs from federal interference, despite June’s written request from Attorney General Jeff Sessions. However, the U.S. House Committee on Rules blocked a number of cannabis-related amendments in September, including the Rohrabacher-Blumenauer amendment.