Congressional investigators have formally asked Trump’s ex-national security adviser, Amb. John Bolton, to testify in their impeachment inquiry, The Daily Beast has confirmed. They’ve asked him to testify on Nov. 7; and they have asked White House lawyers John Eisenberg and Michael Ellis to testify on Nov. 4. 

A lawyer for Bolton did not immediately respond to a request for comment. His attorney, Chuck Cooper, also represents National Security Council official Charles Kupperman, who has sued to ask a federal judge to determine whether or not he should honor a congressional subpoena. Investigators have subpoenaed him, but the White House has directed him not to appear, citing executive branch privileges. It is unclear if Bolton will take the same approach, or will buck the White House’s all-but-certain efforts to block him from testifying. 

Democrats have wanted to hear from Bolton for weeks. The president’s former adviser could be a key witness in their efforts to detail how the Trump administration pushed for the Ukrainian government to investigate former Vice President Joe Biden and his son Hunter. According to whistleblower report released last month, Trump temporarily withheld military support promised to Kyiv to pressure the country’s government into investigating Burisma Holdings, a company where Hunter Biden was a board member. The administration eventually released the aid, but the appearance of a quid pro quo alarmed national security officials.

The situation appears to have riled Bolton. One former White House official, Fiona Hill, told congressional investigators in her testimony that he referred to it as a “drug deal” and advised his subordinates on the NSC to steer clear of it.