President Trump called Colorado Sen. Cory Gardner this week to tell him there will be no crackdown on states that legalized marijuana for recreational use.

Trump also said he will support legislation to allow state autonomy under federal law, which currently makes pot possession for any reason outside limited research a crime.

Gardner, a Republican, won the assurances by blocking Justice Department nominations after Attorney General Jeff Sessions withdrew the so-called Cole Memo in January.

[Related: Jeff Sessions to end policy that let legal marijuana flourish]

That 2013 memo allowed state-regulated recreational pot markets to open by identifying specific trip wires for a federal crackdown.

Sessions, a longtime marijuana legalization opponent, empowered individual U.S. attorneys to decide whether to prosecute marijuana crimes, putting the fate of a multibillion-dollar state-legal industry in question.

Gardner is releasing his holds on Justice Department nominations in response to the president's call.

“Late Wednesday, I received a commitment from the President that the Department of Justice’s rescission of the Cole memo will not impact Colorado’s legal marijuana industry,” Gardner said in a statement.

“Furthermore, President Trump has assured me that he will support a federalism-based legislative solution to fix this states’ rights issue once and for all," he said.

White House press secretary Sarah Sanders said Gardner's statement "is accurate," and that the president called Gardner a second time Friday. She told reporters at the daily White House press briefing that Trump is a "firm believer" in states' rights.

Marc Short, the White House's legislative affairs director, told the Washington Post that Trump “does respect Colorado’s right to decide for themselves how to best approach this issue.”

Short said that “clearly, we’ve expressed our frustration with the delay with a lot of our nominees and feel that too often, senators hijack a nominee for a policy solution. So we’re reluctant to reward that sort of behavior. But at the same time, we’re anxious to get our team at the Department of Justice.”

As a candidate, Trump repeatedly promised to respect state recreational marijuana laws. He also endorsed the legalization of medical marijuana, though he has not publicly addressed these positions since taking office. Sessions, meanwhile, has asked Congress to drop budget language protecting the approximately two-dozen state medical pot markets.

Currently, nine states and the nation’s capital have laws allowing adults 21 and older to possess small amounts of marijuana for recreational use.

Recreational retail markets are open in Alaska, California, Colorado, Nevada, Oregon, and Washington. Officials are working to implement voter-approved laws in Maine and Massachusetts, while Vermont and the nation’s capital have non-commercial legalization laws.

Although the threat of a federal crackdown loomed with Sessions leading the Justice Department, polls have shown overwhelming public support for marijuana legalization. A Pew Research Center poll in January found 61 percent support. A Gallup poll found 64 percent support late last year.