The former national security adviser to Donald Trump has reportedly been summoned by house impeachment investigators to testify before congress next week.
The committees have reportedly asked Mr Bolton to appear on 7 November, while Mr Eisenberg and Mr Ellis have both been asked to testify on 4 November. The depositions have not yet been scheduled.
House investigators have said they are interested in hearing from Mr Bolton after other witnesses testified of his concerns about Mr Trump’s involvement in Ukraine.
The news comes as house Democrats prepared for open public hearings possibly in a matter of weeks as their inquiry moves forward.
They are probing Mr Trump’s 25 July call with Ukrainian president Volodymyr Zelensky urging him to investigate Democrats and the family of Joe Biden as the White House was withholding military aid to the country. There is no evidence of illegal wrongdoing by any of the Bidens.
Mr Trump says he did nothing wrong, while Democrats call it a potentially impeachable offence.
On Wednesday, a State Department foreign service officer told congress that Mr Bolton expressed caution about the role of Rudy Giuliani, Mr Trump’s personal lawyer, as a go-between with Ukraine.
Christopher Anderson and Catherine Croft, another foreign service officer, testified in the house impeachment inquiry.
Mr Anderson told congress about a June meeting with Mr Bolton in which he said he supported increased White House engagement with the Ukraine government.
But Mr Anderson also said Mr Bolton warned that Mr Giuliani was a “key voice with the president on Ukraine” and that that could be an obstacle.
Earlier this month Fiona Hill, a British-born former adviser to the president on Russia, reportedly told the impeachment inquiry that Mr Bolton had referred to efforts to get the Ukrainians to investigate Mr Trump’s political opponents as a “drug deal”, and that he referred to Mr Giuliani as “a hand grenade who’s going to blow everybody up”.
Mr Bolton, a foreign policy hawk who served as US ambassador to the United Nations under president George W Bush, was a surprise appointment as Mr Trump’s national security adviser. He left his job in September with Mr Trump claiming he had been fired and Mr Bolton insisting he had resigned.
The Associated Press contributed to this report
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