The US House of Representatives dealt a blow to President Donald Trump on Monday by rejecting his veto of a defense bill, setting the stage for the Senate to deliver a humiliating first veto override in the final days of his presidency.

The Democratic-controlled House voted 322 to 87 to override Trump's veto of the $740.5 billion defense bill, with 109 members of the president's own Republican Party siding with Democrats.

A similar motion will be introduced in the Republican-majority Senate, where it will also have to gain two-thirds support to override the president's veto.

US President Donald Trump is facing a potential congressional override of his veto of the defense bill
US President Donald Trump is facing a potential congressional override of his veto of the defense bill AFP / ANDREW CABALLERO-REYNOLDS

In a statement released after the vote, Democratic House Speaker Nancy Pelosi slammed Trump's veto as "reckless" and called on the president to "end his eleventh-hour campaign of chaos."

The House vote came a day after Trump caved to pressure from both Republicans and Democrats and reluctantly signed a $900 billion coronavirus relief and stimulus package that he had threatened to veto.

Trump's capitulation on the Covid-19 relief bill and the looming congressional veto override are the latest signs of his waning powers as he prepares to leave the White House on January 20.

The fiscal 2021 National Defense Authorization Act was passed this month by 335 votes to 78 in the House and by 84 to 13 in the Senate.

The $740.5 billion National Defense Authorization Act was passed this month by the Democratic-controlled House and the Republican-majority Senate
The $740.5 billion National Defense Authorization Act was passed this month by the Democratic-controlled House and the Republican-majority Senate GETTY IMAGES / TASOS KATOPODIS

But the NDAA was vetoed by the president because it did not repeal Section 230, a federal law that provides liability protection to internet companies.

Trump also opposed a provision that would strip several US military bases of the names of generals who fought for the secessionist, pro-slavery South in the 1861-65 Civil War.

Including the defense bill, Trump has vetoed nine bills during his four years in the White House. Congress has not previously mustered the votes needed to override any of his vetoes.

US President-elect Joe Biden speaks about foreign policy after a briefing in Wilmington, Delaware
US President-elect Joe Biden speaks about foreign policy after a briefing in Wilmington, Delaware AFP / Brendan Smialowski

For a real estate tycoon who prides himself as a master negotiator, the past few days have been an exercise in humiliation.

Trump threatened for days not to sign the Covid-19 relief and spending bill that had been hammered out by his own treasury secretary and had received broad bipartisan support in Congress.

His surprise move risked shutting down the government from Tuesday and depriving millions of Americans of economic relief badly needed during the pandemic.

The House of Representatives voted to override President Donald Trump's veto of the defense bill
The House of Representatives voted to override President Donald Trump's veto of the defense bill GETTY IMAGES / TASOS KATOPODIS

He finally backed down under bipartisan pressure and signed the bill on Sunday night at his Mar-a-Lago club in Florida, out of sight of television cameras.

But in an attempt to save face, Trump released a statement airing his grievances about the November 3 election and claiming that he had obtained a number of concessions on the relief bill.

Among Trump's demands was increasing direct relief payments to Americans from $600 to $2,000.

The House, in a 275 to 134 vote, approved a motion on Monday to increase the payments to $2,000, but it is likely to meet with resistance from Republicans in the Senate.

Independent Senator Bernie Sanders threatened late Monday to filibuster the veto override bill in the Senate if the upper house did not allow a vote on the extra $2,000 direct payments to Americans.

That would potentially delay the measure and throw extra pressure on the Republicans ahead of two key Senate run-offs in Georgia next month that could determine control of the chamber.

President-elect Joe Biden, asked by a reporter Monday if he favored raising the payouts to $2,000, replied, "Yes."

Biden, speaking after a briefing by his transition team on national security, also said that political appointees at the Pentagon, which Trump has packed with loyalists since the election, have refused to provide a "clear picture" on troop posture or budgeting.

"It is nothing short, in my view, of irresponsibility," Biden said in Wilmington, Delaware, warning that US adversaries could take advantage of the transition.

The strange episode over the relief package highlighted the degree to which Trump has become isolated, spending much of his time playing golf or railing on Twitter about his election loss.

In a sign of his fading influence, the Rupert Murdoch-owned New York Post, one of Trump's most ardent supporters, published an editorial late Sunday telling him to "Stop the Insanity" and acknowledge he lost the election.

"Mr. President, it's time to end this dark charade," the newspaper said.

"We understand, Mr. President, that you're angry that you lost.

"Not as a revolutionary, but as the anarchist holding the match."