The only lawmaker who has been part of three congressional impeachment probes said President Donald Trump's Ukraine scandal “is more serious” than the Watergate scandal of former President Richard Nixon.

The comments of California Democrat Rep. Zoe Lofgren assume significance as the House Intelligence Committee is readying for a vote to approve the probe report on Tuesday. Lofgren currently serves on the House Judiciary Committee.

Four decades ago, Lofgren helped draft articles of impeachment against Nixon as a congressional staffer. She was also on the House Judiciary panel during President Bill Clinton's impeachment. In 1974, Nixon resigned before impeachment proceedings started.

Foreign interference is the core issue in Trump’s case

Speaking at "State of the Union" on CNN, Sunday the veteran lawmaker endorsed the view of House Intelligence Committee Chairman Adam Schiff that Trump's actions are “far more serious” than Watergate.

Lofgren said: “President Nixon's misconduct related to using the levers of government to hide the Watergate burglary but didn't involve other foreign nations.”

According to Lofgren, the founding fathers were concerned about the interference by foreign governments in the country’s political system.

 “Nixon's behavior didn't fall into that range. So in that way, Trump’s conduct is more serious,” she added.

The whistleblower’s complaint against Trump alleges that the President pressured Ukraine to investigate his political rival Joe Biden to help the President’s 2020 re-election bid, and Trump tried to delay the security aid to that country.

Distinguishing Trump’s case with the allegations against Bill Clinton, Lofgren said: “My concern with the Clinton impeachment was there was no high crime or misdemeanor. Lying about sex does not disrupt the constitutional order or threaten national security.”

As far as Trump is concerned, “We're not pursuing President Trump's lying about sex which has nothing to do with undercutting the constitutional order. If we were pursuing Trump because of the cover-up of his affairs, that would be improper. And we're not going to do that.”

Witnesses unknown

Meanwhile, House Judiciary Committee member Rep. Hakeem Jeffries said on Sunday that even members of the committee do not know who the testifying witnesses are.

“The committee hasn’t been provided with that information yet,” Jeffries said.

Fox News quoted Jeffries saying they only know there will be four witnesses who will be constitutional law experts and three are chosen by the Democrats and one by the Republicans. No other details are known.

The Democratic Party lawmaker said he would be happy to hear from any defense witness from Trump’s side why military aid to Ukraine was improperly withheld.

“If the president would like to come forward and present an actual witness who can provide some exculpatory information as to why the aid was withheld, we all would welcome that,” added Jeffries.