The White House said President Donald Trump's top priority was enforcing federal law "whether it's marijuana or immigration."

Attorney General Jeff Sessions' Justice Department rescinded an Obama-era policy on Thursday that had eased enforcement of federal cannabis laws in states that legalized the herb, instead of giving federal prosecutors largesse to pursue criminal charges as they so choose.

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California, the most populous U.S. state, became the largest legal market for cannabis in the world on Monday. Public reaction to the law change has been enthusiastic, with long lines and stock shortages reported at clinics already licensed and open. Other states that permit the regulated sale of marijuana for recreational use include Washington, Oregon, Alaska, and Nevada. Massachusetts and Maine are on track to do so this year, but federal law still prohibits cannabis despite the move to end prohibition.

The Justice Department rescinded four memos outlining guidelines to help federal prosecutors decide whether to enforce laws and growers and sellers of the plant, a move likely to have harsh consequences for the burgeoning cannabis industry. Federal officials declined to say whether they might take legal action against those states where cannabis is legal, saying further steps were "still under consideration."

The policy put in place under Democratic former President Barack Obama, outlined by then-Deputy Attorney General James Cole in a series of memos, had discouraged federal prosecutors from pursuing cannabis-related criminal cases in states that had legalized the drug.

White House spokeswoman Sarah Sanders said President Donald Trump's top priority was enforcing federal law "whether it's marijuana or immigration."

The administration's action drew condemnation from anti-prohibition campaigners and politicians of all stripes in states where the plant has been legalized. They said it trampled on the rights of voters and created uncertainty about how strictly federal drugs laws will be enforced.

The move raised questions about how it might impact tax revenues in states that permit some form of legal cannabis use. It also created uncertainty for banks, already fearful about business relationships with the cannabis industry because of concerns they might run afoul of anti-money laundering rules.

Sessions said that the Obama-era policy "undermines the rule of law" and told federal prosecutors in his memo to "follow the well-established principles that govern all federal prosecutions" in deciding which cannabis-related activities to prosecute.

The Obama-era policy recognized cannabis as a "dangerous drug," but said the Justice Department expected states and localities that authorized various uses to effectively regulate and police it.

The Sessions memo did not distinguish between enforcement against cannabis used for recreational versus medicinal purposes. But his department's ability to pursue criminal charges related to medicinal cannabis remains in doubt.

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Some prosecutors in legalization states issued statements on how they would proceed. A U.S. attorney in Colorado said he would not change his approach toward cannabis prosecutions, while a U.S. attorney in Massachusetts said he would pursue federal cannabis criminal cases.

The Trump administration's action directly contradicts statements that Trump made during the 2016 presidential campaign. The former host of NBC's “The Apprentice” reality show told a TV news reporter that the decision to legalize cannabis should be left "up to the states."

California Lieutenant Governor Gavin Newsom, a Democrat, said his state will pursue "all legal, legislative and political options to protect its reforms and its rights as a state." He said the Trump administration's position "defies facts and logic."

Republican Senator Cory Gardner of Colorado said on Twitter that the administration's action "directly contradicts what Attorney General Sessions told me prior to his confirmation."

Gardner said he would take all steps necessary to fight the measure, including possibly holding up the Senate from voting on pending Justice Department nominees.

However, House Democrats also lined up on Thursday to defend Sessions and keep him as attorney general for as long as special counsel Robert Mueller is investigating collusion between Russia and the Trump campaign, CNN reported.

Since 2014, federal lawmakers have attached language to spending legislation that explicitly bars the Justice Department from spending resources to enforce cases in states where medicinal cannabis is legal.