Democrats accused President Donald Trump of a readiness to sell out US national security to bolster his 2020 reelection effort as hearings opened Wednesday to draw up impeachment charges against the US leader.

But in a fiery start to the House Judiciary Committee's review of the evidence, Republicans countered that Democrats were trying to reverse the 2016 election that brought Trump to power and were pushing towards impeachment without due process.

Trump "directly and explicitly invited foreign interference in our elections," said House Judiciary Committee Chair Jerry Nadler, referring to Trump's effort to get dirt on his Democratic rivals from Ukraine.

"He used the powers of his office to try to make it happen. He sent his agents to make clear that this is what he wanted and demanded," Nadler said.

"He was willing to compromise our security and his office for personal, political gain."

Doug Collins, the senior Republican on the panel, countered with the suggestion the hearing was a partisan political effort to undermine a democratically elected president.

"We're having a factless impeachment," he said, rejecting the final report on the investigation of Trump released on Tuesday.

"We have just a deep-seated hatred of a man who came to the White House and did what he said he was going to do," Collins said, referring to Trump.

"This is not an impeachment. This is just a simple railroad job. And today's is a waste of time."

House Judiciary Chairman Jerry Nadler (R) accused Donald Trump of inviting foreign interference in US elections, while Doug Collins, the senior Republican on the panel, rejected the push to impeach Trump as purely partisan
House Judiciary Chairman Jerry Nadler (R) accused Donald Trump of inviting foreign interference in US elections, while Doug Collins, the senior Republican on the panel, rejected the push to impeach Trump as purely partisan POOL / SAUL LOEB

On Tuesday, congressional Democrats made a forceful case that Trump should be removed from office for abusing his powers by pressuring Ukraine for dirt on a Democratic election rival.

The final report on the House Intelligence Committee's probe, led by lawmaker Adam Schiff, concluded that "the president placed his personal political interests above the national interests of the United States, sought to undermine the integrity of the US presidential election process and endangered US national security."

The 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.

Kicking of the next phase of impeachment, four constitutional scholars were called to testify Wednesday before the House Judiciary Committee in the first of a series of hearings to establish the gravity of Trump's alleged crimes.

In London for a NATO summit, President Donald Trump slammed the Democratic report presenting the case for his impeachment as a "joke" and lambasted his opponents for proceeding with hearings during his trip.

"What they are doing is a very bad thing for our country," Trump said when asked about the report. "It's a joke."

Democrats reportedly aim to have articles of impeachment presented for a vote to the entire House of Representatives before Christmas on December 25.

If they pass as expected, Trump would then stand trial for removal in the Republican-controlled Senate, where he is expected to be exonerated.