US President Donald Trump solicited foreign interference to boost his chances of re-election next year, undermined national security and ordered an "unprecedented" campaign to obstruct Congress, according to a Democratic-led report into his alleged official misconduct.

Key points: The Democrats also allege Mr Trump sought to obstruct their investigation

The Democrats also allege Mr Trump sought to obstruct their investigation The Democratic-led House Intelligence Committee is due to vote on the findings

The Democratic-led House Intelligence Committee is due to vote on the findings Impeachment would ultimately be decided by the Republican-controlled Senate

In a 300-page report that alleged sweeping abuse of power, the Democratic-led House of Representatives Intelligence Committee said Mr Trump had used US military aid and the prospect of a White House visit to pressure his Ukrainian counterpart to undertake probes that would benefit the Republican President politically.

"[Mr Trump] placed his own personal and political interests above the national interests of the United States, sought to undermine the integrity of the US presidential election process, and endangered national security," the report read.

Democrats, who began the formal impeachment inquiry in September, also accused Mr Trump of an "unprecedented" effort to obstruct the investigation, including refusing to provide documents and testimony from his top advisers, unsuccessful attempts to block career Government officials from testifying and intimidation of witnesses.

"Donald Trump is the first president in the history of the United States to seek to completely obstruct an impeachment inquiry undertaken by the House of Representatives," the report said.

The matter is presently being discussed by the House Judiciary Committee.

If the full House eventually votes to approve formal impeachment charges, a trial would be held in the Republican-led US Senate, where a two-thirds majority of those present would be required to convict and remove Mr Trump from office.

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Watch Duration: 2 minutes 2 m Democrat Adam Schiff impeachment was a result of Mr Trump's alleged belief that he was "beyond accountability".

How the impeachment process might end for Donald Trump. ( ABC News: Tim Madden )

Impeachment's origins strike at the origins of the Republic

In his preface to the House impeachment report, Democratic Intelligence Committee chair Adam Schiff invoked the words of the US's first president George Washington.

"[He] warned of a moment when 'cunning, ambitious and unprincipled men will be enabled to subvert the power of the people and to usurp for themselves the reins of government, destroying afterwards the very engines which have lifted them to unjust dominion'," Mr Schiff wrote.

In the Democrats' view, Washington's warning appeared to have manifested in the actions of Mr Trump.

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Watch Duration: 36 seconds 36 s Democrats said they were "protecting the Republic" when they announced formal impeachment proceedings.

House Democrats appear to be contemplating at least two possible articles of impeachment tied to the Ukraine scandal: abuse of power and obstruction of Congress.

While the report noted that damage to the Ukraine-US relationship would be "remedied over time", it said "the damage to our system of checks and balances, and to the balance of power within our three branches of government, will be long-lasting and potentially irrevocable" if Mr Trump's alleged behaviour went unchecked.

The report also pointedly noted that Mr Trump's "misconduct was not an isolated occurrence, nor was it the product of a naive president".

Summarising its findings, the report said many of Mr Trump's "closest subordinates and advisers", including White House acting Chief of Staff Mick Mulvaney, Secretary of State Mike Pompeo and Secretary of Energy Rick Perry, had knowledge of, and in some cases facilitated and furthered Mr Trump's efforts and withheld information.

New phone records lay out pattern of contact

Mr Schiff presented the House's findings alongside a placard carrying quotes from witness testimony. ( AP: Susan Walsh )

Much of the report drew on the public testimony of current and former government officials, who described in televised hearings a months-long effort to pressure Ukraine to carry out the investigations sought by Mr Trump.

It cited dozens of previously unreported phone records that laid out a pattern of contact between Mr Trump's personal lawyer, Rudy Giuliani, Mr Giuliani's associates, the House Intelligence Committee's top Republican, Devin Nunes, and the White House's Office of Management and Budget.

The phone records were obtained from US telecom provider AT&T, the report said.

An AT&T spokesman acknowledged that the telecoms giant complied with a request.

Mr Schiff said the phone records showed there was considerable coordination among the parties, including the White House, and there might be evidence that members of Congress were complicit in illegal activity.

Trump spokesperson labels report 'one-sided sham process'

Mr Trump has consistently denied the accusations made by Democrats. ( Reuters: Tom Brenner )

Mr Trump, who is in London for a NATO summit, has denied any wrongdoing and accused Democrats of using the impeachment process to overturn the results of the 2016 presidential election.

Addressing the allegations he solicited foreign interference in the 2020 election, he said the cloud of impeachment was not undercutting his negotiating position on the international stage.

"I know most of the leaders," Mr Trump said. "I get along with them.

"It's a hoax. The impeachment is a hoax. It's turned out to be a hoax."

Opinion polls show Americans are bitterly divided over whether to impeach him.

Republicans, in an advance rebuttal report released on Monday, claimed Democrats had not established that Mr Trump had committed an impeachable offence.

White House spokeswoman Stephanie Grisham said Democrats led by House Intelligence Committee Chairman Adam Schiff had conducted a "one-sided sham process" that had failed to produce any evidence of wrongdoing by Trump.

"This report reflects nothing more than their frustrations. Chairman Schiff's report reads like the ramblings of a basement blogger straining to prove something when there is evidence of nothing," Ms Grisham said.

ABC/Reuters