WASHINGTON — White House officials will take more time to review a sweeping plan from U.S. health regulators to ban menthol cigarettes, an unexpected delay that anti-tobacco groups fear could scuttle the long-awaited rule.

Administration officials indicated Wednesday the process will continue into next year, targeting March to implement the rule, according to an updated regulatory agenda posted online. Previously, the rule was widely expected to be published in late 2023 or early January.

The Food and Drug Administration has spent years developing the plan to eliminate menthol, estimating it could prevent 300,000 to 650,000 smoking deaths over several decades. Most of those preventable deaths would be among Black Americans, who disproportionately smoke menthols.

Previous FDA efforts on menthol have been derailed by tobacco industry pushback or competing political priorities across several administrations. The latest delay comes amid lingering worries from some Democrats about President Joe Biden's prospects in a rematch against Donald Trump.

Anti-smoking groups have spent years backing the effort. And some warned on Wednesday that the proposal, which would give cigarette companies one year to phase out the flavor, could be held up indefinitely.

"Any delay in finalizing the FDA's menthol rule would be a gift to the tobacco industry at the expense of Black lives," said Yolanda Richardson, CEO of the Campaign for Tobacco-Free Kids. "We urge the administration to keep its promise and issue a final rule by the end of this year."

Menthol is the only cigarette flavor that wasn't banned under the 2009 law that gave the FDA authority over tobacco products. The flavor's cooling effect makes it easier to start smoking and harder to quit, driving menthol's popularity. An estimated 85% of Black smokers buy menthols.

FDA officials sent their final version of the regulation to the White House's Office of Management and Budget in October, typically the last step before a rule is released.

But the White House has agreed to hold dozens of meetings with groups opposing the rule, including civil rights advocates, business owners and law enforcement officials. In nearly all cases, the groups opposing the ban have received donations from tobacco companies.

More than 60 meetings on the rule have been scheduled with budget office staffers, with discussions set to stretch into January, according to a government website. Only three of the meetings thus far have been with health groups, records show.

The meetings underscore the attention the issue is attracting from prominent African American leaders and senior members of the Biden administration.

A Nov. 20 meeting included civil rights attorney Ben Crump and Kendrick Meek, a former congressman who is now a lobbyist with a law firm whose clients include the tobacco company Reynolds American. More than two dozen government officials also attended the virtual meeting, including Food and Drug Administration Commissioner Robert Califf and Health and Human Services Secretary Xavier Becerra.

The meeting was requested by the National Organization of Black Law Enforcement Executives, which has received funding from cigarette-makers, including Reynolds. The group has been running ads in local Washington media warning that a menthol ban would damage relations between police and the communities they serve.

The FDA and health advocates have long rejected such concerns, noting FDA's enforcement of the rule would only apply to companies that make or sell cigarettes, not to individual smokers.