Despite that campaign, several current and former officials braved the president's wrath and testified to the multifaceted effort to sabotage a policy of support for Ukraine that Trump theoretically backed.
The president himself, in London for a North Atlantic Treaty Organisation summit, lambasted his opponents for proceeding with impeachment hearings during his trip.
Meanwhile, Rep. Matt Gaetz said Democrats will be held accountable for continuing to prioritize removing the president from office rather than helping the American people with meaningful legislation.
"As for the hearing scheduled for December 4, we can not fairly be expected to participate in a hearing while the witnesses are yet to be named and while it remains unclear whether the Judiciary Committee will afford the president a fair process through additional hearings", Cipollone told the committee.
"You can have things that meet the legal standard of high crimes and misdemeanors but won't be introduced as article of impeachment because of the politics", the aide said.
"This report chronicles a scheme by the president of the United States to coerce an ally, Ukraine, that is at war with an adversary, Russia, into doing the president's political dirty work", Schiff said on Capitol Hill on Tuesday.
Some Democrats worry that including Mueller's findings in impeachment articles would be divisive for the caucus - particularly among vulnerable moderates who are already wary of the political consequences of an impeachment vote.
Trump "was willing to compromise our security and his office for personal, political gain" by "directly and explicitly" inviting foreign interference in USA elections in 2016 and again in his 2020 reelection effort, the Judiciary Committee chair, New York Democrat Jerry Nadler, said in his opening statement.
White House counsel Pat Cipollone sent a letter to Nadler on Sunday informing him that the White House won't partake in the hearing.
Congressman Doug Collins, the Judiciary panel's top Republican, piled on, calling the inquiry a "railroad job" wasting the American public's time.
Stanford law professor Pamela Karlan delivered powerful testimony Wednesday before the House Judiciary Committee, explaining in simple terms her view that President Trump's conduct warranted his impeachment.
"I see a pattern in which the president's views about the propriety of foreign governments intervening in our election process are the antithesis of what our framers were committed to", Karlan added.
Faced with the revelation of his actions, President Trump publicly and repeatedly persisted in urging foreign governments, including Ukraine and China, to investigate his political opponent.
Even so, the 300-page report approved by the Democrats on the Intelligence, Oversight and Foreign Affairs committees on Tuesday weaves what we have learned over the last few months into a compelling narrative with an inescapable conclusion: Trump has compromised and subverted USA national security interests for his own domestic political purposes and must be held accountable.
"Soliciting itself is the impeachable offense", she said.
If they pass as expected, Trump would then stand trial for removal in the Republican-controlled Senate, where he is likely to be exonerated.