About one week after former Vice President Joe Biden said he opposed legalization in part because marijuana might be a gateway drug, the Democratic presidential candidate is now saying research doesn’t support that position.

In a call with reporters on Monday, the Nevada Independent’s Megan Messerly asked Biden whether he was wrong about suggesting that cannabis was a gateway to harder drugs at an earlier town hall event in Las Vegas.

Biden denied that he made the claim in the first place. “I didn’t,” he said. “I said some say pot was a gateway drug.”

After noting that he supports decriminalization, expunging prior records, releasing those incarcerated for marijuana offenses and rescheduling the plant, the former vice president formally walked back his position on whether existing scientific research demonstrates that cannabis leads to the use of other substances.

“I don’t think it is a gateway drug. There’s no evidence I’ve seen to suggest that.”

Click the image above to see the full transcript.

“That has been my position and continues to be my position,” he said.

“With regard to the total legalization of it, there are some in the medical community who say it needs to be made a Schedule II drug so there can be research studies, as not whether it is a gateway drug but whether or not it, when used in other combinations, may have a negative impact on people overcoming other problems, including in fact on young people in terms of brain development—a whole range of things that are beyond my expertise. There are serious medical folks who say we should study it more. Not that we should make it illegal, that we should be in a position where we criminalize it but where we should look at it.”

Listen to Joe Biden’s new marijuana comments below:

Audio courtesy of KUNR Public Radio.

These latest comments are a lot different from what the former vice president said just last week. At the town hall, Biden said “there’s not nearly been enough evidence that has been acquired as to whether or not it is a gateway drug.”

“It’s a debate, and I want a lot more before I legalize it nationally,” he said. “I want to make sure we know a lot more about the science behind it.”

Evidently, Biden took a crash course on cannabis in recent days.

Shortly after he made the gateway drug remarks, numerous high-profile lawmakers took him to task for peddling what’s widely considered a debunked theory.

Rep. Alexandria Ocasio-Cortez (D-NY), for example, described the former vice president’s remarks as a “Reagan-era talking point.”

Sens. Bernie Sanders (I-VT) and Kamala Harris (D-CA), who are also presidential candidates, seemed to criticize Biden shortly after reports of the comments surfaced, implicitly contrasting their comprehensive legalization proposals with the former vice president’s stance.

Entrepreneur Andrew Yang, who is also running for the Democratic nomination, accurately predicted that Biden’s position would shift, though perhaps sooner than he anticipated.

The criticism over Biden’s comments culminated during last week’s presidential debate, where Sen. Cory Booker (D-NJ) proactively called out the former official for opposing cannabis legalization when it’s “already legal for privileged people, and the war on drugs has been a war on black and brown people.”

The senator’s mother wasn’t too keen on his joke about Biden being high when he made those remarks, however.

Shortly after Biden’s comments were publicized on Monday, Booker’s national press secretary, Sabrina Singh, questioned why the former vice president is maintaining his opposition to legalization when he now acknowledges that cannabis is not a gateway drug.

“If @JoeBiden finally agrees with @CoryBooker that marijuana is not a gateway drug, then why does he still oppose federal legalization?” she tweeted.

But while the former vice president’s present opposition to legalization puts him at odds with other candidates on the stage and the majority of the American public, it’s not the only drug policy critique he’s faced. Civil rights groups have similarly highlighted that Biden played a key role in advancing punitive anti-drug laws during his time in the Senate—legislative actions that will presumably be harder to walk back than an off-hand remark.