A member of the State Department's science envoy program resigned Wednesday and took a parting shot at the president on his way out.
Daniel Kammen, a professor of energy at the University of California, Berkeley, tweeted early Wednesday he is departing from his role as a science envoy to the State Department.
In his accompanying resignation letter, several sharp-eyed Twitter users spotted a curious acrostic from the first letter in each paragraph that seemed to spell out a message about Donald Trump: "IMPEACH."
Kammen has served in various roles for the Department of Energy, the Environmental Protection Agency and the State Department since 1996.
Asked for comment, State Department spokeswoman Julia Mason said: "Today, Dr. Daniel Kammen made a personal decision to resign. We appreciate his dedicated service to U.S. scientific diplomacy during his appointment working on energy efficiency and renewable energy in Africa as a Science Envoy."
The science envoy program website notes Kammen's work in renewable energies. Reviving the coal industry was a major campaign issue for Trump. In late March, he signed an executive order reversing the Obama administration's Clean Power Plan, which would have closed coal-fired power plants and frozen construction on new ones while replacing them with wind and solar farms.
Last week, a business council advising Trump disbanded after a string of high-profile resignations, starting with Merck CEO Kenneth Frazier, following Trump's response to the racist violence in Charlottesville.
The State Department's website lists six other science envoys.