In an eight-page letter to House Speaker Nancy Pelosi, the White House declares it will not cooperate with the impeachment probe.
"You have designed and implemented your inquiry in a manner that violates fundamental fairness and constitutionally mandated due process," wrote White House counsel Pat Cipollone. "President Trump cannot permit his administration to participate in this partisan inquiry under these circumstances."
Pelosi says the move amounts to obstruction of justice.
"This letter is manifestly wrong and is simply another unlawful attempt to hide the facts," she said in a statement.
Democrats also issued a subpoena for Gordon Sondland, the US Ambassador to the European Union after the State Department directed him not to testify to the committee earlier Tuesday.
Sondland is of interest because of what he knew about the investigation into Joe Biden and his son and the holdup of US aid to Ukraine.
Tuesday House Intelligence Committee Chairman Adam Schiff revealed details about a text exchange involving Sondland and others.
"We know from the text messages that Ambassador Sondland was in discussion with Ukrainian counterparts, with fellow diplomatic personnel, and the President, and at least one US senator, about the course of events we are investigating," said Schiff.
Text messages show another US diplomat to Ukraine was concerned, but Sondland texted the president was clear, "No quid pro quo."
House Republicans are defending President Trump.
"What we see in this impeachment is a kangaroo court and chairmanship is acting like a malicious Captain Kangaroo," said Rep. Matt Gaetz (R-FL).
The pushback from the White House could move the House to push a vote on impeachment sooner and add obstruction of justice charge.
In the Senate, Lindsey Graham (R-SC) wants to have Trump's personal attorney Rudy Giuliani testify about the investigation into the Bidens' conduct in Ukraine.
He said in a tweet, "Have heard on numerous occasions disturbing allegations by @rudygiuliani about corruption in Ukraine and the many improprieties surrounding the firing of former Prosecutor-General Viktor Shokin."
Have heard on numerous occasions disturbing allegations by @RudyGiuliani about corruption in Ukraine and the many improprieties surrounding the firing of former Prosecutor General Viktor Shokin.
— Lindsey Graham (@LindseyGrahamSC) October 8, 2019
As the impeachment inquiry continues, former GOP Rep. Trey Gowdy is considering joining the President's legal team as outside counsel.
Meanwhile, there are new revelations about the whistleblower who set off the impeachment inquiry. The Washington Examiner reports that the Inspector General says the whistleblower had a professional relationship with one of the Democratic candidates in the 2020 election.