Donald Trump snubbed a handshake from Democrat house speaker Nancy Pelosi as he entered Congress to deliver a thunderous State of the Union address before she dramatically tore up a copy of his speech.

The US president astonishingly ignored the outstretched hand of Pelosi and then proceeded to tear into his enemies and opponents.

After Trump's unprecedented snub, Pelosi tore up a copy of his speech just as the president finished the address as tensions in US politics dramatically boiled over.

Pelosi, who dropped her opposition to impeachment and allowed Democratic lawmakers to seek charges against the president, had sat stoically and grim-faced behind Trump throughout.

Tomorrow, the Republican-backed Senate is set to acquit Trump after his impeachment trial.

In Congress, he was met by chants of 'four more years' from jubilant Republicans, as Democrat lawmakers sat stony-faced as Trump boasted: "The state of our union has never been stronger."

Verbal fireworks were inevitable in a speech that lasted longer than an hour, as he confronted the Democrat opponents who approved articles of impeachment against him.

But the dramatic scenes that unfolded were nevertheless remarkable.

Trump ignored Pelosi's hand as he gave her a copy of his remarks before starting his speech.

Having not spoken to Trump since their last meeting, Pelosi appeared to be taken aback.

She avoided citing the customary "high privilege and distinct honor" that usually accompanies the speaker's introduction of the president to Congress.

"Members of Congress, the President of the United States" was all she said in introducing Trump.

When his speech ended, Pelosi stood and tore up her copy of the remarks he had handed her.

She later told reporters she did it as it was "the courteous thing to do, considering the alternative."

The House Speaker also shared a photo of the snubbed handshake, saying "Democrats will never stop extending the hand of friendship to get the job done".

In his address, Trump went on to proclaim "we will never let socialism destroy American healthcare!" while he also called for a ban to late-term abortions.