Zeller credited Gottlieb for advocating for the nicotine regulation within the Trump White House, after the Obama administration had fallen short. Obama officials had promised Zeller they would back rules to curb nicotine and menthol.

The FDA's proposed rule would slash nicotine levels in cigarettes, most cigars and other combustible tobacco products, but not vapes, hookahs or Zyn.

The move could help millions of Americans quit smoking while preventing many more from becoming addicted. The proposed rule, published Wednesday in a 334-page report, would cap nicotine levels in cigarettes and other tobacco products,