Former Vice President Joe Biden (D) said on Saturday that he’s not sure if marijuana is a gateway drug that leads to the use of other, more dangerous substances.

“The truth of the matter is, there’s not nearly been enough evidence that has been acquired as to whether or not it is a gateway drug,” the 2020 presidential candidate claimed at a town hall meeting in Las Vegas. “It’s a debate, and I want a lot more before I legalize it nationally. I want to make sure we know a lot more about the science behind it.”

That said, Biden added that while he doesn’t personally support ending cannabis prohibition, “states should be able to make a judgement to legalize marijuana.”

“I think that’s OK,” he said.

Biden, who in past years has clearly said he thinks cannabis is a gateway drug and has a long record of supporting legislation to ramp up the war on drugs, was answering a voter’s question about whether his position on marijuana has changed.

“No, it hasn’t changed,” he told the town hall participant.

In 2010, the then-vice president said, “I still believe it’s a gateway drug. I’ve spent a lot of my life as chairman of the Judiciary Committee dealing with this. I think it would be a mistake to legalize.”

Earlier this year Biden’s campaign said he now supports a modest reclassification of cannabis under federal law—moving it from the most restrictive category of Schedule I to Schedule II—and that he backs the decriminalization of its possession.

In the town hall, Biden appeared to say he supports moving cannabis even further down the list to Schedule III, though he may have misspoke, because he initially said that the drug is currently classified in Schedule II before correcting himself to say it falls under Schedule I.

Watch Biden’s marijuana remarks, about 37:30 into the video below:

Biden also said in the new comments that he supports medical cannabis and that marijuana possession “should not be a crime.”

“It should be, to the extent that it exists, and anyone ever been convicted of the use of marijuana and put in jail, they should be immediately released, their record should immediately be expunged,” he said. “It should not be a crime. It should be a civil penalty to the extent that it exists in states that don’t choose to legalize… But no one should go to jail for it, period.”

But in a September debate, Biden said marijuana “should be a misdemeanor.”

At the Las Vegas town hall, the presidential candidate said that he needs to see more science and data to determine whether cannabis is a gateway drug and to inform his position on national legalization.

“It is not irrational to do more scientific investigation to determine, which we have not done significantly enough, whether or not there are any things that relate to whether it’s a gateway drug or not. I don’t know enough to know whether it is, although I’ve done a great deal of work on the drug side of this issue,” he said.

‘Nationally I’m not prepared to push for the legalization,” Biden continued. “Medical marijuana, yes, but the legalization of marijuana for recreational use in fact is one that I need more data to make that judgement.”

The National Institute on Drug Abuse says that “the majority of people who use marijuana do not go on to use other, ‘harder’ substances.”

A 1999 Institute of Medicine report found that cannabis “does not appear to be a gateway drug to the extent that it is the cause or even that it is the most significant predictor of serious drug abuse; that is, care must be taken not to attribute cause to association.”

Several studies have indicated that states where people have legal access to marijuana see reductions in opioid overdoses or that patients who use medical cannabis reduce their consumption of prescription painkillers.

The House Judiciary Committee plans to vote on a bill to federally legalize marijuana this week, according to two sources with knowledge of the soon-to-be-announced action.

This piece was first published by Forbes.