Sen. Cory Gardner (R-CO) is threatening to block future nominees for Department of Justice positions in response to Attorney General Jeff Sessions’ planned announcement Thursday of a new, potentially tougher policy on marijuana.

Sessions plans to rescind a 2013 memo, issued under the Obama administration, that indicated that the Justice Department would refrain from enforcing federal drug laws in states that had legalized marijuana. Instead, the department will now leave enforcement and prosecution decisions up to individual U.S. Attorneys in each state.

The effect of the new approach could be to increase the uncertainty surrounding marijuana cultivation and sales, which have flourished over the past few years in Colorado and other states, like California, that have legalized it. Sessions’s new policy could also bring federal law enforcement into conflict with state authorities.

Gardner tweeted that President Trump original “had it right” when he suggested in 2016 that marijuana policy should be left to the states:

.@realDonaldTrump had it right. This must be left up to the states. https://t.co/azxZlIc7Vg — Cory Gardner (@SenCoryGardner) January 4, 2018

.@realDonaldTrump had it right. This must be left up to the states. https://t.co/azxZlIc7Vg — Cory Gardner (@SenCoryGardner) January 4, 2018

I am prepared to take all steps necessary, including holding DOJ nominees, until the Attorney General lives up to the commitment he made to me prior to his confirmation. — Cory Gardner (@SenCoryGardner) January 4, 2018

Under the new policy, marijuana would be one of the only areas in which the Trump administration has increased federal regulation of an industry.

Sessions was previously known to be a staunch critic of marijuana legalization.

Joel B. Pollak is Senior Editor-at-Large at Breitbart News. He was named to Forward’s 50 “most influential” Jews in 2017. He is the co-author of How Trump Won: The Inside Story of a Revolution, is available from Regnery. Follow him on Twitter at @joelpollak.