Image copyright AP Image caption A protest in Los Angeles against Donald Trump's bill. The healthcare debate has been an emotional one

US President Donald Trump has demanded a make-or-break vote in the House of Representatives on Friday on his troubled healthcare bill.

The American Health Care Act is meant to replace parts of President Barack Obama's signature "Obamacare" law.

A vote on Thursday was delayed because of opposition from some Republicans.

Mr Trump reportedly told fellow Republicans that they had a choice between voting for his bill on Friday or being stuck with Obamacare for good.

The president made the warning during a closed-door meeting at the White House, US media reported.

High stakes for Trump on healthcare vote

All-male US health bill photo sparks anger

A debate on the bill is now taking place in the House of Representatives, with a vote due later on Friday.

Republican and House Speaker Paul Ryan said: "For seven-and-a-half years we have been promising the American people that we will repeal and replace this broken law because it's collapsing and it's failing families, and tomorrow we're proceeding."

Image copyright EPA Image caption Mr Trump had a meeting with truckers at the White House, but hit a roadblock in the House

Chris Collins, a New York Republican who supports Mr Trump, said on Thursday evening: "The president has said he wants a vote tomorrow, up or down. If for any reason it is down, we are just going to move forward with additional parts of his agenda."

Mr Trump kept up the pressure on Friday morning, tweeting: "After seven horrible years of ObamaCare (skyrocketing premiums & deductibles, bad healthcare), this is finally your chance for a great plan!"

Another tweet targeted the conservative Freedom Caucus, many of whose members have opposed the bill.

Woefully unpopular bill - Analysis by Anthony Zurcher, BBC Washington

The moment Republicans have been anticipating for seven years has almost arrived. They will have the chance to take a major first step toward rolling back the healthcare reform passed by Barack Obama and Democrats.

So why is it that almost no Republicans seem happy?

Moderates are upset that the proposed legislation cuts health coverage too much. Hard-liners are angry the changes don't go far enough. Donald Trump is warning that if things don't go his way, he'll abandon the whole effort.

The president's move effectively forces the hand of recalcitrant members of Congress. The moderates seem unlikely to budge, so it all comes down to the libertarian-leaning Freedom Caucus conservatives. Is a half a repeal loaf better than no loaf at all?

Looming over all of this is the stark reality that the proposed legislation is woefully unpopular with the public at large - garnering just 17% approval in one recent poll. Conservative interest groups are sharply divided over whether to support the bill or not.

What should have been a moment of triumph for Republicans in Congress has turned into an exercise in political pain minimalisation.

Repealing and replacing Obamacare was a major plank of Mr Trump's election campaign, but its replacement has stalled amid Republican infighting, with the current reforms going too far for some and not far enough for others.

The postponement of Thursday's vote was a setback for the president, who had insisted he would win the numbers to pass it through the lower chamber of Congress on that day.

Media playback is unsupported on your device Media caption Healthcare battle in rural America

He needs a minimum of 216 Republicans to vote for the bill. If 22 join the Democrats, the bill will fail.

But US media tallies suggest between 28 and 35 Republicans still remain opposed it.

The administration's hope is that Mr Trump's ultimatum will force them to vote Yes, if the alternative is the preservation of Mr Obama's healthcare legislation.

White House budget director Mick Mulvaney told ABC News: "Lawmakers will have to be accountable as to why they didn't vote to get rid of Obamacare when they had the chance, and that chance is today."

But even if the bill does pass, it could face a tougher passage in the Senate, where Republicans have only a 52-48 majority.

Earlier on Thursday, House Minority Leader Nancy Pelosi said Mr Trump had made a "rookie's error for bringing this up on a day when clearly you're not ready".

More on the healthcare story

Media playback is unsupported on your device Media caption What's in the Republican healthcare bill?

Obamacare helped 20 million previously uninsured Americans get health insurance but has been plagued by increases in insurance premiums, which were also a problem before the health law.

Mr Trump promised a new law that would cover more people and at a lower cost.

The Republican bill keeps some of the popular elements of Obamacare but limits future federal funding for Medicaid, which covers low-income people.

A new estimate by the Congressional Budget Office released on Thursday evening said recent changes to the bill would make it costlier than previously thought.

The number of uninsured Americans would rise by 24 million by 2026 under the new law, the budget analysis said.

Groups representing doctors, hospitals and the elderly have said they are opposed to the Republican bill.

Key elements of the new bill: