A coalition of conservative groups led by Americans for Tax Reform is urging the Trump administration to abandon its plan to ban flavored e-cigarette sales.
The Food and Drug Administration (FDA) is expected to issued guidance on the prohibition soon, arguing the flavors are appealing to children and leading to rising youth vaping rates.
But conservatives say the ban, which doesn't apply to tobacco flavors, would hurt small vape businesses and adults trying to quit cigarettes.
"Eliminating all but one or two of these options for adults would destroy thousands of small businesses, force many adult vapers to return to smoking, and force some to seek out products on the black market," the groups wrote in a letter to President Trump on Thursday.
The groups, which include the American Conservative Union and FreedomWorks, argue the ban would force thousands of "mom-and-pop" vape shops to close.
"Unchallenged, the FDA will destroy thousands of small businesses without Congressional oversight and without sufficient input from the public," the groups wrote.
The White House canceled a meeting with conservative groups last week that was intended to focus on their concerns. A White House official told Bloomberg News it would be rescheduled.
The administration's plan has garnered bipartisan support in Congress.
Trump, the FDA and the Department of Health and Human Services announced the plan last month in the Oval Office, with the president calling the flavor ban necessary amid an outbreak of vaping-related illnesses. He also cited rising youth vaping rates.
Health officials at the FDA and the Centers for Disease Control and Prevention (CDC) don't know what is causing the illnesses, which have killed at least 16 people and sickened more than 800.
The CDC said last week products containing THC, the psychoactive compound in cannabis, are playing a role in the outbreak.
But it's not known if the illnesses are caused by THC, nicotine or any number of the chemicals that are often found in vape liquids.
The CDC also said last week that most of the illnesses in Illinois and Wisconsin had been linked to THC products sold under the name "Dank Vapes," which doesn't appear to be a legitimate manufacturer.