"I am hopeful that you and your counsel will opt to participate in the Committee's hearing, consistent with the rules of decorum and with the solemn nature before us", judiciary committee Chairman Jerrold Nadler said in a letter announcing the hearing, which is titled, "The Impeachment Inquiry into President Donald J. Trump: Constitutional Grounds for Presidential Impeachment".
President Donald Trump was briefed on the whistleblower complaint about his dealings with Ukraine before the White House released almost $400 million in military aid to Kyiv, officials say, shedding new light on events that triggered the impeachment inquiry.
A whistle-blower complaint would typically be submitted to lawmakers who have oversight of the intelligence agencies.
The Times report says Trump's lawyers briefed the president in late August about the complaint as they were attempting to determine whether they were legally required to give it to Congress. Michael Atkinson, the inspector general for the intelligence community, concluded it should be. There will undoubtedly be hand-wringing about this in the five days between now and when the committee needs to know whether they should expect White House counsel.
A Trump administration official has told The Washington Post that the White House has been unable to find any record of the September 9 call between President Donald Trump and the USA ambassador to the European Union, Gordon Sondland.
The new timeline suggests Trump was aware his dealings with Ukraine were under scrutiny before he started issuing denials that he sought something from Ukraine.
The White House Office of Management and Budget made its first official move to withhold military aid to Ukraine on July 25, the same dayPresident Donald Trump spoke to Ukrainian President Volodymyr Zelenskiy by phone, according to a summary of OMB documents produced by the House Budget Committee.
The White House has declined to comment.
The whistleblower complaint was filed in August and the security aid block was lifted in September. "Rudy very much knows what's happening and he is a very capable guy", Trump said to Zelenskiy, according to a rough transcript released by the White House. Duffey has refused to testify before House impeachment investigators despite being served with a subpoena on October 25.
The aid was released on 11 September amid growing pressure from members of Congress.
That evening, an OMB career official signed a document formally withholding $250 million in Pentagon funds for Ukraine, the Washington Post reported, citing the summary.
At the heart of the inquiry is whether Trump committed "high crimes and misdemeanors", which is vaguely defined in the U.S. Constitution.
He has been invited by the Democratic chairman of the House Judiciary Committee to attend the impeachment hearing on December 4.
"At base, the president has a choice to make", Mr Nadler said.
The complaint alleged that Trump improperly leveraged USA military aid to coerce the opening of politically beneficial investigations during his July 25 phone call with Ukrainian president Volodymyr Zelensky.
They have also argued that the funding's eventual release proves that Trump did nothing wrong.
Trump has seized on the call as evidence that he was not trying to benefit personally from his dealings with Ukraine.
Other impeachment witnesses have recalled Sondland telling them about a calls before the alleged September 9 call - on September 1 and September 7 - in which the president told him he wanted no "quid pro quo", but did want Ukrainian president to personally announce a Biden probe.
Trump has repeatedly slammed the impeachment inquiry as a political "witch hunt" by Democrats.