Donald Trump has reacted furiously to the impeachment push against him after Speaker Nancy Pelosi ordered formal charges be drawn up.

In a historic announcement, Ms Pelosi said she had requested the US House of Representatives begin drafting articles of impeachment that stipulated the charges against the President.

Mr Trump will have to front these “charges” if the House votes to send them to the Senate for trial.

“No one is above the law,” Ms Pelosi said as she warned that Mr Trump had “abused his power”.

“Our democracy is what is at stake; the President leaves us no choice but to act,” she said.

Ms Pelosi said Mr Trump’s actions over the Ukraine incident that sparked the impeachment inquiry were “a profound violation of the public trust” and “have seriously violated the constitution”.

“His (Mr Trump’s) wrongdoing strikes at the very heart of our constitution,” she said.

The move drew an immediate reaction from Mr Trump, who goaded Ms Pelosi even before she had made her announcement.

The President tweeted, urging Ms Pelosi to “do it now” so the country could move on.

“They have no Impeachment case and are demeaning our Country,” he said.

“But nothing matters to them, they have gone crazy. Therefore I say, if you are going to impeach me, do it now, fast, so we can have a fair trial in the Senate, and so that our Country can get back to business.”

After the announcement, Mr Trump fired off a further flurry of tweets, saying Ms Pelosi had “just had a nervous fit” and accusing the Democrats of wanting to “impeach me over NOTHING”.

The Do Nothing, Radical Left Democrats have just announced that they are going to seek to Impeach me over NOTHING. They already gave up on the ridiculous Mueller “stuff,” so now they hang their hats on two totally appropriate (perfect) phone calls with the Ukrainian President….

— Donald J. Trump (@realDonaldTrump) December 5, 2019

Ms Pelosi’s announcement follows weeks of public and closed door hearings in which witnesses were interviewed as part of a fact-finding probe.

Mr Trump is accused of using his position to pressure Ukraine to investigate his main political rival, Joe Biden, by withholding military aid.

During Ms Pelosi’s media conference, a journalist asked if she “hated” Mr Trump, to which she responded: “I don’t hate anyone”.

“I was raised in a way that is a heart full of love and always pray for the President. … So don’t mess with me when it comes to words like that,” she said.

What happens next?

Once articles of impeachment are drawn up, the House will vote on whether to bring charges – which will be done by a simple majority.

A full House impeachment vote could happen by the end of December.  Democrats control the House and could impeach Mr Trump without Republican support.

If the House approves articles of impeachment, a trial will then beheld in the Senate, which is controlled by Republicans. Conviction and removal of a president would require a two-thirds majority, although a conviction seems unlikely.

No US president has ever been removed as a direct result of impeachment. Richard Nixon resigned before he could be removed while Andrew Johnson and Bill Clinton were impeached by the House but not convicted by the Senate.

In the unlikely event the Senate convicts Mr Trump, Vice-President Mike Pence will become president for the remainder of Mr Trump’s term, which ends on January 20, 2021.

Immediately after Ms Pelosi’s announcement, White House press secretary Stephanie Grisham said the Democrats “should be ashamed”.

The US House Judiciary Committee later announced it will hold a hearing on Monday to receive presentations of evidence in the impeachment inquiry.

Lawyers representing Democrats and Republicans from the intelligence and judiciary committees will make the presentations, Representative Jerrold Nadler, the Democrat head of the judiciary committee, said.

-with AAP