Democrats unveil impeachment inquiry plan detailing a 'clear path forward'

House Democrats unveiled a resolution on Tuesday authorizing and laying out procedures for the next phase of the impeachment inquiry against Donald Trump, saying it will provide “a clear path forward” as the House begins a public phase of the investigation.

“This is a sad time for our country,” said Democratic congressman James McGovern, the chairman of the House Rules Committee. “None of us came to Congress to impeach a president, but each of us took a solemn oath to protect and defend the constitution.”

The resolution came on a day of alarming testimony regarding Trump’s 25 July call with the Ukranian president, Volodymyr Zelenskiy, which was central to the whistleblower complaint that sparked the impeachment inquiry.

On Tuesday, Alexander Vindman, a former army colonel and diplomat, told House investigators that he listened to the Trump-Zelenskiy call and escalated his concerns.

“I was concerned by the call,” Vindman said, according to written testimony obtained by the Associated Press. “I did not think it was proper to demand that a foreign government investigate a US citizen, and I was worried about the implications for the US government’s support of Ukraine.”

Top Democrats later said his testimony was “extremely disturbing” and called him “very credible”.

The impeachment inquiry up to this point has largely consisted of closed-door interviews, led by the House intelligence, oversight and foreign affairs committees. Under the process proposed by the resolution, the intelligence committee will take control, leading any public hearings.

The president and his allies have complained that the inquiry so far has been too secretive and denied Trump any chance to defend himself.

The White House made clear that the resolution had not changed its opinion; a statement from the press secretary, Stephanie Grisham, called it a “scam” and complained that the Trump administration was being denied “basic due process rights”.

House Republicans are unlikely to support the resolution. “You can’t put the genie back in the bottle,” the House minority leader, Kevin McCarthy, told the Washington Post on Tuesday. “Due process starts from the beginning.”

The House rules committees is expected to consider and possibly amend the impeachment resolution tomorrow afternoon, with a vote on the proposal still set for Thursday.

The impeachment resolution notes that, at the beginning of public hearings, the chairman and ranking member of the House intelligence committee – Democrat Adam Schiff and Republican Devin Nunes – can ask witnesses questions for up to 45 minutes each before proceeding to other committee members. (They may also defer to a committee staffer.)

The resolution also allows for the public release of transcripts from interviews so far, “with appropriate redactions to protect classified and other sensitive information”.

According to the resolution, the House intelligence committee will take the lead on planning public hearings as the inquiry advances.

Related: Army officer's impeachment testimony is a quandary for Republicans

The resolution also establishes that Republicans may ask to hear testimony from certain witnesses, but those requests will be declined or approved by Schiff. This procedure is in line with the rules for the minority party during the 1998 impeachment of Bill Clinton, according to the Washington Post.

In a statement, House committee leaders said: “The evidence we have already collected paints the picture of a president who abused his power by using multiple levers of government to press a foreign country to interfere in the 2020 election.

“Following in the footsteps of previous impeachment inquiries, the next phase will move from closed depositions to open hearings where the American people will learn firsthand about the president’s misconduct.”

Pressure on Trump in the impeachment inquiry is mounting rapidly. And when the hearings become public, many Americans will for the first time encounter the damaging accusations against Trump from the witnesses making them. A recent poll found that a majority of people now support the investigation.

Tom McCarthy and agencies contributed reporting