US House Speaker Nancy Pelosi has accused the President of throwing a "temper tantrum" at a meeting with Democratic congressional leaders, openly questioning his fitness and suggesting a family or staff "intervention" after a dramatic blow-up at a White House meeting.

Key points: Ms Pelosi said Mr Trump has established a pattern of unpredictability

Ms Pelosi said Mr Trump has established a pattern of unpredictability Ms Pelosi has accused Mr Trump of a "cover-up" in regard to Russian election meddling

Ms Pelosi has accused Mr Trump of a "cover-up" in regard to Russian election meddling Mr Trump said it was impossible to work on such legislation as long as Democrats continued their "phony" investigations of him

Both Republican President Donald Trump and Democratic leaders dug in a day after Mr Trump stalked out of the Cabinet Room demanding an end to congressional investigations before he would work with Congress on crumbling US infrastructure and other matters.

In a second consecutive day of tough words about Mr Trump, Ms Pelosi accused the President of obstruction of justice, which she said was an impeachable offense.

"Again, I pray for the President of the United States. I wish that his family, or his administration, or his staff would have an intervention for the good of the country," Ms Pelosi told reporters.

Ms Pelosi said Mr Trump has established a pattern of unpredictability and at one point even joked about the constitution's provision laying out the procedure for replacing a president.

"For some reason, maybe it was lack of confidence on his part … he took a pass, and it just makes me wonder why he did that," she said.

'Phony investigations'

On Wednesday, shortly before a previously scheduled meeting with Mr Trump at the White House to discuss infrastructure investment legislation, Ms Pelosi accused Mr Trump of a "cover-up" in regard to investigations related to Russia's meddling in the 2016 US elections.

Her remarks rankled Mr Trump and prompted him to walk out of the infrastructure meeting after just three minutes, possibly sinking the legislation's prospects.

Loading

Mr Trump said it was impossible to work on such legislation as long as Democrats were continuing their "phony" investigations of him.

At her weekly news conference on Thursday, Ms Pelosi remained on the attack, repeating her contention from the previous day that Mr Trump was incapable of working on complex legislative issues.

"I can only think that he wasn't up to the task of figuring out the difficult choices of how to cover the cost of … the important infrastructure legislation that we had talked about three weeks before."

While she raised the issue of obstruction, Ms Pelosi also said that House Democrats were not yet prepared to launch formal impeachment proceedings against Mr Trump.

Even though Mr Trump has indicated that he is not willing to engage in bipartisan work on legislation as long as House Democrats are investigating him, both Ms Pelosi and Senate Democratic Leader Chuck Schumer on Thursday challenged Republicans in Congress to leave the Republican President behind and continue working on legislation without him if he is unwilling to engage.

Politicians are trying to put the finishing touches on a long-delayed disaster aid bill.

Meanwhile, Republican and Democratic leaders in Congress want to strike a two-year deal on federal spending levels and raising the US Treasury Department's borrowing authority.

Ms Pelosi said House Democrats were not yet prepared to launch formal impeachment proceedings against Mr Trump. ( AP: Evan Vucci )

ABC/Wires