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 US 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, according to US media reports.

Even if recategorised, cannabis will remain illegal at the federal level. However, 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 US 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 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 US news outlets have reported that the announcement may also include a pilot program that would see some older Americans reimbursed for cannabidiol (CBD) for conditions including cancer treatments.

In recent years, a majority of US 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 stated that he was considering the reclassification due to the 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 became bogged down under administrative and legal issues.

Trump has expressed a desire to change US drug policy regarding cannabis, advocating for ending arrests for personal use and implementing smart regulations for access to safe products.

The reclassification proposal has faced resistance from some Republican lawmakers. Recently, 22 Republican Senators sent an open letter to the president arguing that marijuana use would hinder re-industrialization efforts in America.

Polls indicate a majority of Americans support legalizing marijuana, though recent surveys show a slight decline in support among Republicans.