Photographer: Stefani Reynolds/Bloomberg

Senator Elizabeth Warren reiterated her call for Rick Perry to resign from his role with Energy Transfer LP, citing recent media reports that he pushed for a deal involving the company while he was U.S. Energy Secretary.

“Your actions raise even more questions about your behavior during your time in government service,” Warren said in a letter dated Wednesday that was seen by Bloomberg. She referred to stories published by Time and ProPublica that said Perry worked to advance an ultimately unsuccessful natural gas transaction with Ukraine that would have involved Energy Transfer. “You should rectify your mistake and immediately resign from your position on the board of directors of Energy Transfer,” she said.

Perry, a two-time U.S. presidential candidate, was appointed Jan. 1 to the board of LE GP LLC, the so-called general partner that controls Energy Transfer. Dallas billionaire Kelcy Warren -- no relation to Elizabeth Warren -- has a majority stake in LE.

Energy Transfer is pleased to have Perry as a board member of LE, Vicki Granado, a spokeswoman for the company, said in an email. A spokesman for Perry didn’t immediately respond to a request for comment.

Warren, a Democratic senator for Massachusetts, said in correspondence in January that Perry’s decision to join the board weeks after leaving Donald Trump‘s administration was “unethical” because Energy Transfer lobbied the department he oversaw.

Warren said in her latest letter that policies overseen by Perry directly benefited the fossil fuel industry, “including Energy Transfer and its role building and promoting controversial fossil fuel infrastructure.”