Billionaire Elon Musk has delivered a scathing opinion of US President Donald Trump's key tax and spending bill, describing it as "a disgusting abomination."

Tuesday's remarks by Musk, considered a major Trump ally, come shortly after he withdrew from Washington at the end of his work for the administration, where he led the Department of Government Efficiency, better known as DOGE.

The bill, which Trump has named the "Big Beautiful Bill," has so far passed the House of Representatives but is being held up in the Senate by several Republicans who want more cuts to spending.

What did Musk and others say?

"This massive, outrageous, pork-filled Congressional spending bill is a disgusting abomination," Musk posted on his site X, formerly Twitter.

 "Shame on those who voted for it: you know you did wrong. You know it."

He added that the bill would "massively increase the already gigantic budget deficit to $2.5 trillion (!!!) and burden America citizens with crushingly unsustainable debt."

In response to the comments,  White House Press Secretary Karoline Leavitt said: "Look, the president already knows where Elon Musk stood on this bill. It doesn't change the president's opinion. This is one big, beautiful bill, and he's sticking to it."

However, Musk's comments received unexpected support from independent Senator Bernie Sanders, who wrote, "Musk is right," also calling the bill an "abomination."

Sanders, a fierce Trump critic who describes himself as a democratic socialist and is allied with the Democratic Party, wrote that the bill would give the richest Americans $664 billion (€584 billion) in tax breaks while $290 billion would be cut from food aid for the impoverished.

Trump's bill aims to extend tax breaks from his first term, financing them partly by cuts in social benefits.

Edited by: Elizabeth Schumacher