The Trump administration is causing serious paranoia among marijuana advocates with its hints of a federal crackdown on recreational use. But Attorney General Jeff Sessions has privately reassured some Republican senators that he won't deviate from an Obama-era policy of allowing states to implement their own marijuana laws.

Sessions has rattled both libertarians and liberals in ordering a review of the hands-off pot policy under President Barack Obama. But Sessions provided some private assurances to senators before he was confirmed that he was not considering a major shift in enforcement, despite his opposition to the use of marijuana.

And since he was confirmed, Sen. Cory Gardner (R-Colo.) said administration officials have left him with the impression there is no big policy change coming.“He told me he would have some respect for states' right on these things. And so I’ll be very unhappy if the federal government decides to go into Colorado and Washington and all of these places. And that’s not the [what] my interpretation of my conversation with him was. That this wasn’t his intention," said Sen. Rand Paul (R-Ky.). in an interview.

"Nothing at this point has changed," Gardner said.

But a large group of bipartisan senators aren't taking any chances. They sent a letter on on Thursday urging Sessions to uphold the Obama-era policy of allowing states to implement their recreational marijuana laws, after the Trump administration has indicated it could crack down on marijuana.

The effort is led by Sens. Elizabeth Warren (D-Mass.) and Lisa Murkowski (R-Alaska), who hail from states that have legalized marijuana. Press secretary Sean Spicer has hinted at "greater enforcement" of federal laws treating marijuana as an illegal drug. Sessions said this week that he is "dubious about marijuana" and is reviewing current policy.

But senators are beginning to push back.

"We respectfully request that you uphold DOJ's existing policy regarding states that have implemented strong and effective regulations for recreational use," the senators wrote to Sessions. "It is critical that states continue to implement these laws."

Eight states and the District of Columbia have legalized marijuana for recreational use. Most of the senators who signed on to the letter hail from those states; Murkowski is the only Republican. The senators who signed the letter in addition to Warren and Murkowski are Democratic Sens. Patty Murray of Washington, Ron Wyden of Oregon, Jeff Merkley of Oregon, Maria Cantwell of Washington, Ed Markey of Massachusetts, Brian Schatz of Hawaii, Catherine Cortez Masto of Nevada, Cory Booker of New Jersey and Michael Bennet of Colorado.

"Do they really respect states' rights? Then you should respect all of them, not just pick and choose the ones that you want to support or not. Many states have gone not only the path of Nevada of recreational marijuana but medical marijuana. How can you pick or choose one or another?" Cortez Masto said in an interview.

Cortez Masto's GOP colleage, Sen. Dean Heller, separately disclosed that he discussed his state's marijuana policy with Sessions during the nomination process in a letter to Sessions. Heller also urged Sessions to keep current policy.

"While I maintain that, unlike medical marijuana, I have serious concerns on whether or not the benefits of recreational marijuana outweigh the drawbacks, I recognize and respect the will of Nevadans," Heller wrote on Wednesday.

But a Justice Department spokesman said senators should mellow out. "The department’s current policy is reflected in the 2013 Cole Memo," the DOJ spokesman said, referring to the Obama policy.

The concern, however, isn't just among senators from states that have legalized the drug. It's also an issue for conservatives who are worried about the GOP selectively allowing states' rights to supercede federal law.

"We’re concerned about some of the language that we’re hearing. And I think that conservatives who are for states' rights ought to believe in states' rights. I'm going to continue to advocate that the states should be left alone," Paul said.

Gardner, whose home state was a pioneer in legalizing the drug, was less alarmed by the statements coming from Sessions and Spicer.

“He was talking about if there’s cartels involved in illegal operations, they’re going to crack down on that. That’s what everybody’s saying. I still haven’t heard Jeff Sessions say that" there's a big policy change coming, Gardner said. "We obviously want to make sure we're clear on what they’ve said."

However, Sessions came awfully close earlier this week to suggest sweeping changes are coming, saying that the Obama-era policy is under review.

"I'm definitely not a fan of expanded use of marijuana," Sessions told reporters. "States they can pass the laws they choose. I would just say it does remain a violation of federal law to distribute marijuana throughout any place in the United States, whether a state legalizes it or not."

In an interview, Murkowski said she was not yet alarmed, but was monitoring the Justice Department closely.

"It's probably a little premature to try to predict what may or may not be coming out of the administration on this, so I think we just need to sit back and see," she said.