File photo. Photograph:( AFP )
Democrats have made a forceful case that Trump should be impeached for trying to leverage a White House meeting
Three constitutional scholars on Wednesday bolstered Democrats' case for impeaching Donald Trump by saying the president's actions seeking foreign interference in US elections were clear grounds for removal, as the inquiry kicked into high gear in Congress.
But reflecting the Washington political divide, a fourth expert strongly dissented, saying there was "woefully inadequate" evidence that Trump committed high crimes and misdemeanours necessary for removal.
Democrats have made a forceful case that Trump should be impeached for trying to leverage a White House meeting and military aid to pressure Ukraine for dirt on an election rival.
In a theatrical hearing of the House Judiciary Committee, now tasked with weighing impeachment charges against the president -- lawmakers listened to damning testimony from constitutional law professors.
"On the basis of the testimony and evidence before the House, President Trump has committed impeachable high crimes and misdemeanours by corruptly abusing the office of the presidency," Harvard Law School professor Noah Feldman told the hearing.
"We three are unanimous" in that view, jurisprudence professor Michael Gerhardt of the University of North Carolina stated, referring to himself and fellow witnesses Feldman and Stanford Law School professor Pamela Karlan.
The trio was invited by Democrats to testify.
Americans tuning in to the eight-hour live broadcast witnessed clashes between Democrats and Republican Trump loyalists on the panel, who repeatedly forced procedural votes to stall the process.
The new phase of impeachment began a day after a congressional report on the high-stakes inquiry detailed "overwhelming" evidence of abuse of power and obstruction by the president.
The report mapped out a months-long scheme by Trump, his personal lawyer Rudy Giuliani, senior diplomats and White House staffers to pressure Ukraine's president into investigating Joe Biden, the current favourite to win the Democratic nomination for the 2020 election.
Trump "was willing to compromise our security and his office for personal, political gain," said Judiciary Committee chairman Jerry Nadler.
Watch: Democrats release impeachment report on Donald Trump
'Proof, not presumptions'
Trump's alleged political crimes, including bribery and obstruction of justice and Congress, "are worse than the misconduct of any prior president," Gerhardt said.
"If what we're talking about is not impeachable, then nothing is impeachable."
Feldman added that if Trump is not held to account for his offences "we live under a dictatorship."
White House spokeswoman Stephanie Grisham hit back in a statement, saying that "the only thing the three liberal professors established at chairman Nadler's hearing was their political bias against the president."
"It did nothing to change the fact that, despite weeks of hearings in this sham process, the president did nothing wrong," Grisham said.
The fourth academic who testified, George Washington University Law School professor Jonathan Turley -- the only expert invited by Republicans -- argued there was "no evidence" that Trump acted with corrupt intent.
He warned that partisan "rage" was compromising the inquiry.
"Impeachments have to be based on proof, not presumptions," he said, adding that Democrats were rushing the process so quickly that they were not hearing from key players in the Ukraine scandal.
Turley and Republicans did not, however, mention the White House's stonewalling. Despite Democratic requests, 12 current or former administration officials have refused to testify.
The president himself, in London for a NATO summit, lambasted his opponents for proceeding with impeachment hearings.
"What they are doing is a very bad thing for our country," Trump said. "It's a joke."
Karlan asserted that Trump's alleged effort to withhold military aid until Ukraine committed to investigating Biden was grounds for removal -- even though Kiev never conducted the probe.
"Soliciting itself is the impeachable offence," she said.
But Karlan found herself in hot water when she invoked Trump's 13-year-old son Barron when differentiating between monarchical and presidential power.
"While the president can name his son 'Barron,' he can't make him a baron," Karlan said.
The remark drew stiff blowback from First Lady Melania Trump, and Karlan apologized.
The House Intelligence Committee report is expected to form the basis for the Judiciary Committee to draw up formal charges -- articles of impeachment -- that could include bribery, abuse of power, obstruction and contempt of Congress.
Democrats reportedly aim to have the articles presented for a vote to the entire House of Representatives by late December.
If the House impeaches Trump, he would then stand trial for removal in the Republican-controlled Senate, where he is likely to be exonerated.
The Senate meanwhile released its 2020 schedule, and the entire month of January is blocked off, signalling preparations for a trial.