Donald trump on sunday raised the prospect of the supreme court striking down the affordable care act just a day after announcing his third nominee to the us high court.

The healthcare law introduced under barack obama is set to be a key flash point in next months confirmation hearings for amy coney barrett, mr trumps supreme court nominee.

Ms barrett has previously criticised a 2012 supreme court ruling that narrowly upheld the aca, also known as obamacare. the court is set to consider the law again in november just a week after the presidential election.

Obamacare will be replaced with a much better, and far cheaper, alternative if it is terminated in the supreme court. would be a big win for the usa! mr trump tweeted. the trump administration has been arguing in court for the law to be struck down.

Though democrats currently lack the votes in the senate to block ms barretts appointment, they are hoping to use the confirmation process to elevate the issue of healthcare in the minds of voters ahead of the november 3 election.

The american people understand that theyre being cut out of this process theyre entitled to be part order to take away the aca, and their healthcare in the midst of a pandemic, said joe biden, the democratic presidential candidate, at an event in wilmington, delaware.

Nancy pelosi, the democratic speaker of the house of representatives, told cnn on sunday: anyone that president trump would have appointed was there to undo the affordable care act. that is why he was in such a hurry.

The aca was signed into law by mr obama in 2010 and has so far largely survived repeated legal challenges from conservatives. more than 20 million americans have gained healthcare coverage since its passing. the act also bans insurers from discriminating against people with pre-existing conditions.

In 2012, chief justice john roberts sided with the supreme courts liberal wing in a 5-4 ruling that said it was constitutional. ms barrett in 2017 criticised that ruling in a law review article, arguing that mr roberts had pushed the affordable care act beyond its plausible meaning to save the statute.

On november 10, the supreme court will hear arguments about the aca again. the law had imposed a penalty on americans who did not purchase healthcare insurance, an individual mandate that the 2012 ruling interpreted as a tax, but congress in 2017 set the penalty at zero.

A texas judge in 2018 ruled that the entire law was therefore unconstitutional. the supreme court, with ms barretts likely appointment giving the court a 6-3 conservative majority, is set to rule on that question, along with whether the rest of the law can stand if the individual mandate falls.

The republican-controlled senate judiciary committee has announced three to four days of hearings on ms barretts nomination, starting on october 12.

Polling published by the new york times on sunday showed that 56 per cent of voters believed that the winner of the forthcoming presidential election should nominate a successor to ruth bader ginsburg, the liberal supreme court justice who died this month.

In a fox & friends weekend interview, mr trump also said it was possible that the court, with three of his nominees, would rule on roe v wade, the decision that created a constitutional right to abortion in the us.maybe they do it in a different way. maybe they'd give it back to the states, mr trump said. the president has previously vowed only to pick justices who would overturn roe v wade.