DEMOCRATS have announced two articles of impeachment against Donald Trump – abuse of power and obstruction of Congress – pushing towards historic votes over charges he corrupted the US election process and endangered national security.

Lawyers for House Democrats outlined their findings so far, saying Trump’s push to have Ukraine investigate rival Joe Biden while at the same time withholding US military aid contradicted US policy and benefited Russia as well as himself.

Judiciary Committee chairman Jerrold Nadler was blunt as he opened the hearing, saying: “President Trump put himself before country.”

House of Representatives speaker Nancy Pelosi, flanked by the chairmen of the impeachment inquiry committees, stood at the Capitol for what she called a "solemn act".

READ MORE: Is impeachment the start of the endgame for President Trump?

Voting is expected in days on the Judiciary Committee and by Christmas in the full House. Trump insisted he did nothing wrong and his re-election campaign called it "rank partisanship".

"He endangers our democracy, he endangers our national security," said Jerrold Nadler, the Democratic chairman of the Judiciary Committee, as he announced the charges. "Our next election is at risk. That is why we must act now."

The president tweeted that impeaching a president with a record like his would be "sheer Political Madness!"

The House has only voted three times in history against a president. Approval of the charges would send them to the Senate in January, where the Republican majority would be unlikely to convict Trump.

Democratic leaders say he put his political interests above those of the nation when he asked Ukraine to investigate his rivals, including Democrat Joe Biden, and then withheld 400 million dollars in military aid as the US ally faced an aggressive Russia.

In drafting the articles of impeachment, Pelosi faced a legal and political challenge of balancing the views of her majority while hitting the constitution's bar of "treason, bribery or other high crimes and misdemeanours".