President Donald Trump is expected to sign an executive order that would expand access to cannabis, a long-anticipated move that would mark the most significant shift in U.S. drug policy in decades.

The order is expected to reclassify cannabis from a Schedule I narcotic to a Schedule III drug - placing it under the same category as Tylenol with codeine, U.S. media reports suggest.

Even if recategorized, cannabis will remain illegal at the federal level. But classifying it as a Schedule III narcotic would allow expanded research to be conducted into its potential benefits.

Several Republican lawmakers have cautioned against the move, with some arguing it could normalize cannabis use.

The U.S. Drug Enforcement Agency notes that Schedule III narcotics - which also include ketamine and anabolic steroids - have only a moderate to low potential for physical and psychological dependence.

The executive order could come as early as Thursday, although the timing could shift, CBS, the BBC's U.S. partner, has reported.

The new classification could also have tax implications for state-authorized cannabis dispensaries, as current regulations bar them from some tax deductions if they sell Schedule I products.

Various U.S. news outlets have reported that the announcement may also include a pilot program that would see some older Americans reimbursed for cannabidiol, commonly known as CBD, for conditions including cancer treatments.

In recent years, a majority of U.S. states have approved cannabis for some medical use, and nearly half - 24 - have legalized recreational use. But since 1971, cannabis has been a Schedule I narcotic, which means it has no accepted medical use and a high potential to be abused.

Earlier this week, Trump said that he was considering the reclassification because of tremendous amounts of research that can't be done unless you reclassify.

The Biden administration proposed a similar reclassification, and in April 2024, the DEA proposed a rule change, but got bogged down under administrative and legal issues.

Trump has long expressed a desire to change U.S. drug policy regarding cannabis.

I believe it is time to end endless arrests and incarcerations of adults for small amounts of marijuana for personal use, he wrote on Truth Social last year while running for president.

We must also implement smart regulations while providing access for adults to safe, tested products, he said.

The reclassification proposal has met some resistance from Republican lawmakers.

On Wednesday, a group of 22 Republican Senators sent an open letter to the president, arguing that marijuana use would mean that we cannot re-industrialize America.

The Senators pointed to lingering concerns over the health impact of cannabis, as well as research suggesting that cannabis can be linked to impaired judgment and lack of concentration.

In light of the documented dangers of marijuana, facilitating the growth of the marijuana industry is at odds with growing our economy and encouraging healthy lifestyles for Americans.

In a separate letter sent to Attorney General Pam Bondi in August, nine Republican representatives argued that no adequate science or data exists to support the change.

Marijuana, while different than heroin, still has the potential for abuse and has no scientifically proven medical value, the letter said. Therefore, rescheduling marijuana would not only be objectively wrong, but it would also imply to our children that marijuana is safe. That couldn't be further from the truth.

More broadly, polls show that a majority of Americans support efforts to legalize marijuana.

One Gallup poll released in November found that 64% of Americans believe that it should be legalized, although support had drifted slightly from previous years because of a 13-point drop among Republicans.