NEW YORK (DPA) - A top foreign policy adviser with direct knowledge of President Donald Trump's push for Ukrainian investigations into Democratic rivals resigned late Wednesday (Oct 30), freeing himself of his White House chains less than 24 hours before he was set to testify in the impeachment inquiry, according to an administration official.
Mr Tim Morrison, a senior member of the White House National Security Council, informed his superiors that he has "decided to pursue other opportunities," the official told the New York Daily News, speaking on condition of anonymity.
The official said Mr Morrison has been considering his departure "for some time". "We wish him well," the person added.
The resignation announcement came one day before Mr Morrison was expected to go before impeachment investigators and discuss Mr Trump's attempts to pressure Ukrainian officials to investigate former Vice-President Joe Biden and other Democrats while using nearly US$400 million (S$544 million) in US military aid as leverage in an apparent quid pro quo.
Earlier on Wednesday, Democrats set the stage for certain House approval of a resolution proposing a new set of rules for the remainder of the impeachment inquiry.
The resolution, which will be voted on by the full chamber on Thursday, was approved by the House Rules Committee following an at-times hostile debate between the panel's Republican and Democratic members.
The measure, which marks the first formal House blessing of the more than month-long impeachment inquiry, will authorise the public release of transcripts from closed-door depositions, pave the way for public hearings and give Mr Trump and his Republican allies more due process rights, including the ability to request subpoenas and cross-examine witnesses.
Despite having called for such a resolution for weeks, House Republican leaders say their members will vote against it because they maintain the measure should have been passed before the inquiry began.
As the House approves the new rules, Mr Morrison - who was Mr Trump's top adviser on Russian and European affairs - is expected to corroborate key details under scrutiny by impeachment investigators.
He has been referenced as a crucial witness in previous depositions and listened in on the July 25 phone call on which Mr Trump allegedly pressured Ukrainian President Volodymyr Zelensky to launch politically laced investigations before the 2020 election.
Mr Bill Taylor, the top US diplomat in Ukraine, testified last week that Mr Morrison told him Mr Trump wouldn't release the US military assistance to Ukraine unless Mr Zelensky publicly committed to investigating Mr Biden and his son, Hunter, as well as unfounded right-wing conspiracy theories about the 2016 election.
Mr Morrison's apparent assertion contradicts the White House's claim that there was no quid pro quo and also undermines testimony from Mr Gordon Sondland, Mr Trump's hand-picked ambassador to the European Union.
Mr Taylor also testified that Mr Morrison told him he experienced a "sinking feeling" after learning that Mr Trump had informed Mr Sondland on Sept 7 about his preconditions for releasing the US aid, which Ukraine relies on to stave off Russia's invasion of Crimea.
Impeachment investigators are likely to press Mr Morrison to explain that "sinking feeling."
Having been brought into the administration by former national security adviser John Bolton, Mr Morrison is set to become the first political appointee to testify in the inquiry.
Republicans on the three committees leading the impeachment investigation will likely be hard-pressed to criticise Mr Morrison, who for years served as a GOP staff member on the House Armed Services Committee before being tapped by Mr Trump to join the administration.
Also on Wednesday, Mr Bolton was invited by impeachment investigators to testify in the inquiry on Nov 7, according to a source familiar with the matter.
Mr Bolton, who clashed repeatedly with Mr Trump over Ukraine policy before he was unceremoniously dumped last month, would become the most senior official to testify so far.
An attorney for the hawkish ex-statesman did not return a request for comment.
In addition to inviting Mr Bolton, impeachment investigators kept busy Wednesday by grilling Ms Catherine Croft and Mr Christopher Anderson, a couple of lesser-known State Department officials, behind closed doors.
Both officials testified that Mr Bolton often raised concern over Trump attorney Rudy Giuliani's oversized sway over the president in all matters relating to Ukraine, according to their prepared opening statements.
Mr Anderson recalled Mr Bolton as once describing Mr Giuliani, Mr Trump's personal lawyer, as "an obstacle" to better US relations with Ukraine.
While Ms Croft and Mr Anderson testified, Mr Trump's own Russia ambassador pick, current Deputy Secretary of State John Sullivan, broke with the president on the Ukraine scandal when pressed by Democrats during his Senate confirmation hearing.
"Soliciting investigations into a domestic political opponent - I don't think that would be in accord with our values," Mr Sullivan said.