President Trump said Friday that he "probably" will support new legislation allowing states to set their own marijuana policies, making good on assurances he gave Sen. Cory Gardner, R-Colo., this year.

The bill sponsored by Gardner would federally legalize marijuana in states that allows its use, ending a long-standing conflict between state and federal law, which still deems almost all possession of the drug illegal.

"I support Sen. Gardner. I know exactly what he's doing," Trump said. "We're looking at it. But I probably will end up supporting that, yes."

In April, Trump told Gardner in a pair of private phone conversations that he would back such legislation, but Trump did not publicly discuss his position.

More than two dozen states allow medical marijuana sales. Nine states and the nation's capital have recreational legalization laws, though neither Vermont or D.C. regulate sales.

During the 2016 campaign, Trump said he favored a states-rights approach to recreational pot and that he supported medical marijuana. But his nomination of Attorney General Jeff Sessions, a longtime reform opponent, generated concern among the state-legal industry.

Gardner won Trump's initial backing on pot reform legislation by blocking Justice Department nominations after Sessions withdrew the 2013 Cole Memo in January. That memo acted as a green light for states' autonomy by identifying specific trip wires for a federal crackdown, and Sessions' move was seen as a threat by states like Colorado. Sessions instead empowered individual U.S. attorneys to decide whether to prosecute marijuana crimes.

Gardner introduced the new legislation with co-sponsor Sen. Elizabeth Warren, D-Mass. A House companion bill is sponsored by Reps. David Joyce, R-Ohio, and Earl Blumenauer, D-Ore. Gardner said he spoke with Trump Thursday before introducing the bill.

The Strengthening the Tenth Amendment Through Entrusting States Act, or the STATES Act, would change federal law to say that the federal Controlled Substances Act doesn't apply to state regulated markets. It sets a 21-year age requirement for recreational sales, and removes industrial hemp, or low-THC cannabis, from the CSA, making it legal to grow nationwide. It would also ease banking hurdles to state legal pot businesses.

"I was glad to hear the President’s comments this morning and his continued interest in an approach that respects the will of the voters in each state regarding the prohibition or legalization of marijuana," Gardner said in a statement. “My legislation is in line with what President Trump said on the campaign and what he and I have discussed several times since he was elected. This is a states’ right issue."