WASHINGTON — A bill that would protect state marijuana laws from federal interference received a major plug on Friday when President Donald Trump said he probably would back the measure, introduced a day earlier by two U.S. senators.

“(I) probably will end up supporting” it, Trump told reporters during a 20-minute exchange with reporters at the White House, according to pool reports.

In the U.S., 46 states and several territories have legalized marijuana in some fashion, but the drug remains illegal under federal law. The bill, by Cory Gardner, R-Colo., and Elizabeth Warren, D-Mass., would force Washington to respect state laws on pot, from medical applications to recreational use.

Because marijuana is illegal at the federal level, cannabis companies face a number of financial obstacles — the biggest being their inability to use banks or bank services. The Gardner-Warren bill would lift that restriction.

Still, there would be limitations. For example, the sale of marijuana would be prohibited at rest areas and truck stops, according to a bill summary.

Trump’s comments Friday build on an earlier discussion he had with Gardner on marijuana.

Gardner, in Denver on Friday for the Western Conservative Summit, welcomed Trump’s comment on the bill.

“It is a positive sign. I had spoken to the president (Thursday) morning, before we had introduced the bill, making sure he was familiar with the legislative efforts and reminding him what we had talked about before — about his decision to approach this through a state’s rights lens,” Gardner said. “He liked the idea — the concept — and, of course, this morning you saw the same thing where he said that he supported the efforts, he knows exactly what I’m doing and most likely will support it.”

The measure also got the backing of Colorado Gov. John Hickenlooper, who Friday was one of a dozen governors who signed a letter of support.

“The federal government needs to provide states adequate space to self govern,” said Hickenlooper. “The issue can no longer be avoided. Ultimately, collaboration with the states will prove critical as the federal government begins to engage on cannabis issues.”

In April, Gardner agreed to end a weeks-long blockade of nominees to the U.S. Department of Justice — one that started over the agency’s marijuana policies — when Trump told him that his administration wouldn’t mess with Colorado’s cannabis industry.

Trump told him: “You have my support for a legislative solution that will allow a states’ rights approach,” Gardner said at the time.

Staff writer Jesse Paul contributed to this article.