Hollywood stars have reacted jubilantly after US President Donald Trump pulled his Obamacare repeal bill.

House Speaker Paul Ryan and Trump announced the move after it became clear that the voting process would end in failure.

The decision, which was made just minutes before the vote was due to take place, is being viewed as a significant setback for Trump, who promised to repeal and replace Obamacare throughout much of his campaign.

Ryan told Trump just ahead of the scheduled Friday vote that there were too many dissenting Republicans to pass the American Health Care Act.

The White House could only afford to have 22 Republicans vote 'no' on the bill.

John Legend, Mark Ruffalo, Michael Moore and George Takei were among those who took to Twitter shortly after to comment on Trump's defeat.

It's no secret that Hollywood and Trump's relationship is hardly a good one - particularly since Trump announced plans to cut government funding for the arts.

Ruffalo wrote: "Congratulations to the #Resistance for win on Health Care."

Moore mocked the business mogul turned-president's deal making skills with a nod his 1987 book: "So much for the Art of the Deal."

In a statement made at a hastily-arranged news conference, Trump said "we learned about loyalty" in the process of the bill's failure.