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.

Officials proposed limiting the amount of nicotine to make cigarettes less addictive, but it's unclear if the incoming administration will offer support.

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