President Donald Trump left the door open Friday on whether he will back a bipartisan effort to shield states that have legalized marijuana for recreational and medical purposes from federal crackdowns.

Before departing the White House for the G-7 Summit, Trump told reporters that the White House is looking at the legislation, which U.S. Sens. Elizabeth Warren, D-Massachusetts, and Cory Gardner, R-Colorado, unveiled Thursday.

The president hinted that he may endorse the measure, adding that he supports Gardner's efforts to address the discrepancy between state and federal marijuana statutes, which has impacted the industry's access to banking, among other things.

"I really do, I support Sen. Gardner. I know exactly what he's doing," he told reporters when asked about the bipartisan effort. "We're looking at it. But, I probably will end up supporting that, yes."

Gardner told reporters Thursday that he had discussed the legislation with Trump, whom he had previously pushed to assure states that their rights would not be infringed by the administration's decision to roll back an Obama-era policy regarding marijuana enforcement.

The Colorado Republican and Warren noted that the "Strengthening the Tenth Amendment Through Entrusting States," or STATES Act, comes in response to Attorney General Jeff Sessions' January decision to rescind the memo that directed U.S. attorneys to not prosecute marijuana crimes in states where the drug had been legalized.

According to the sponsors, the bill looks to amend the Controlled Substances Act so it no longer applies to any person acting in compliance with state or tribal laws when it comes to manufacturing, producing, possessing, distributing, dispensing, administering or delivering marijuana -- as long as states and tribes comply with a few basic protections.

It also seeks to address financial issues caused by the current federal prohibition by stating that compliant transactions are not trafficking and do not result in proceeds of an unlawful transaction.

The measure would further: modify the federal definition of marijuana to exclude industrial hemp; prohibit distribution of marijuana at transportation facilities, like rest areas and truck stops; bar sales of marijuana to those under age 21 except for medical purposes; and maintain protections against endangering human life while manufacturing a controlled substance, as well as prohibitions on employing those under age 18 in marijuana operations.

U.S. Reps. David Joyce, R-Ohio, and Earl Blumenauer, D-Oregon, offered a companion measure in the House.