Senator Bernie Sanders, a former presidential candidate, has gained a co-sponsor for his bill that would create a “Medicare-for-all” healthcare system in the US.

Democratic Senator Kamala Harris of California announced she will co-sponsor Mr Sanders’ single-payer legislation, because “health care is a right”, she tweeted.

While defending the current healthcare law, the Affordable Care Act, Mr Sanders declared earlier this year that the way forward in the long-term was a “Medicare-for-all” single-payer system – a federally administered programme that would abolish the role of private insurers in basic healthcare coverage.

Republicans unsuccessfully tried to dismantle the ACA, otherwise known as Obamacare, in July.

A major plank of Mr Sanders’ 2016 presidential campaign, single-payer healthcare is a system in which the government, generally through taxes, covers basic healthcare costs for all residents regardless of income, occupation or health status.

“I intend to co-sponsor the 'Medicare for All' bill because it’s just the right thing to do,” Ms Harris announced at a town hall in Oakland, California, according to CNN.

“This is about understanding, again, that healthcare should be a right, not a privilege. And it's also about being smart,” Ms Harris added. “It is so much better that people have meaningful access to affordable health care at every stage of life, from birth on. Because the alternative is that we as taxpayers otherwise are paying huge amounts of money for them to get their health care in an emergency room.

“So it's not only about what is morally and ethically right, it also makes sense from a fiscal standpoint, or if you want to talk about it as a return on investment for taxpayers.”

Mr Sanders expressed his appreciation for Ms Harris’ endorsement on Twitter: “Thank you Kamala Harris for your support. Let's make health care a right, not a privilege,” he wrote.

Bernie Sanders campaigns with Hillary Clinton Show all 15 1 /15 Bernie Sanders campaigns with Hillary Clinton Bernie Sanders campaigns with Hillary Clinton Democratic presidential candidate Hillary Clinton, followed by Sen. Bernie Sanders, I-Vt. arrives for a rally in Portsmouth, N.H., Tuesday, July 12, 2016. Andrew Harnik/AP Bernie Sanders campaigns with Hillary Clinton A woman holds a sign at an event where Bernie Sanders will appear with Hillary Clinton at Portsmouth High School July 12, 2016 in Portsmouth, New Hampshire. Sanders and Clinton are expected to show unity within the party and a forwarding of their agendas. Darren McCollester/Getty Bernie Sanders campaigns with Hillary Clinton Cerys Coffey, 5, of North Hampton, Massachusetts, walks along a line of supporters waiting to get into a campaign event with Democratic U.S. presidential candidates Hillary Clinton and Senator Bernie Sanders in Portsmouth, New Hampshire, U.S., July 12, 2016. Mary Schwalm/Reuters Bernie Sanders campaigns with Hillary Clinton Democratic U.S. presidential candidate Hillary Clinton and Sen. Bernie Sanders stand together during a campaign rally where Sanders endorsed Clinton in Portsmouth, New Hampshire, U.S., July 12, 2016. Brian Snyder/Reuters Bernie Sanders campaigns with Hillary Clinton Democratic U.S. presidential candidate Hillary Clinton and Sen. Bernie Sanders greet supporters during a campaign rally where Sanders endorsed Clinton in Portsmouth, New Hampshire, U.S., July 12, 2016. Brian Snyder/Reuters Bernie Sanders campaigns with Hillary Clinton Democratic U.S. presidential candidate Hillary Clinton speaks as Senator Bernie Sanders looks on after he endorsed her during a campaign rally in Portsmouth, New Hampshire, U.S., July 12, 2016. Brian Snyder/Reuters Bernie Sanders campaigns with Hillary Clinton Democratic U.S. presidential candidate Hillary Clinton (R) looks on as Senator Bernie Sanders endorses her during a campaign rally in Portsmouth, New Hampshire, U.S., July 12, 2016. Brian Snyder/Reuters Bernie Sanders campaigns with Hillary Clinton Democratic U.S. presidential candidate Hillary Clinton looks on as Senator Bernie Sanders endorses her during a campaign rally in Portsmouth, New Hampshire, U.S., July 12, 2016. Brian Snyder/Reuters Bernie Sanders campaigns with Hillary Clinton Democratic presidential candidate Hillary Clinton, followed by Sen. Bernie Sanders, I-Vt., arrives for a rally in Portsmouth, N.H., Tuesday, July 12, 2016, where Sanders endorsed Clinton for president. Andrew Harnik/AP Bernie Sanders campaigns with Hillary Clinton Sen. Bernie Sanders, I-Vt. waves as he a Democratic presidential candidate Hillary Clinton arrive for a rally in Portsmouth, N.H., Tuesday, July 12, 2016. Andrew Harnik/AP Bernie Sanders campaigns with Hillary Clinton People hold signs outside an event where Bernie Sanders will appear with Hillary Clinton at Portsmouth High School July 12, 2016 in Portsmouth, New Hampshire. Sanders and Clinton are expected to show unity within the party and a forwarding of their agendas. Darren McCollester/Getty Bernie Sanders campaigns with Hillary Clinton Supporters for Democratic presidential candidates Hillary Clinton and Sen. Bernie Sanders, I-Vt. cheer before a rally in Portsmouth, N.H., Tuesday, July 12, 2016, prior to the arrival of Clinton and Sanders. Sanders is poised to offer his long-awaited endorsement of Clinton, hoping to transfer the energy of his supporters into the party's fight against Republican Donald Trump. Andrew Harnik/AP Bernie Sanders campaigns with Hillary Clinton Supporters of Democratic presidential candidate Hillary Clinton sing the national anthem in Portsmouth, N.H., Tuesday, July 12, 2016, prior to a rally with Democratic presidential candidates Hillary Clinton and Sen. Bernie Sanders, I-Vt. Sanders is poised to offer his long-awaited endorsement of Democratic rival Hillary Clinton, hoping to transfer the energy of his supporters into the party's fight against Republican Donald Trump. Andrew Harnik/AP Bernie Sanders campaigns with Hillary Clinton Supporters of Democratic presidential candidate Hillary Clinton sing the national anthem in Portsmouth, N.H., Tuesday, July 12, 2016, prior to a rally with Democratic presidential candidates Hillary Clinton and Sen. Bernie Sanders, I-Vt. Sanders is poised to offer his long-awaited endorsement of Democratic rival Hillary Clinton, hoping to transfer the energy of his supporters into the party's fight against Republican Donald Trump. Andrew Harnik/AP Bernie Sanders campaigns with Hillary Clinton A woman holds poster for Democratic presidential candidate Hillary Clinton during a rally in Portsmouth, N.H., Tuesday, July 12, 2016, where Sen. Bernie Sanders, I-Vt. endorsed her for president. Andrew Harnik/AP

Ms Harris and Mr Sanders, an Independent who caucuses with the Democrats, are expected to introduce their legislation next month. But the move could further divide Democrats on a key issue as the party seeks to regain its footing at the state and national levels.

Even though more Democrats appear willing to embrace a shift away from the private health insurance market and toward a government-run programme, other members of the party have conveyed concerns about the costs and details associated with establishing a single-payer system in the US.

During the presidential campaign, Hillary Clinton, who Mr Sanders challenged for the Democratic nomination, called the proposal “a theoretical debate about some better idea that will never, ever come to pass.”

An Urban Institute study of Mr Sanders’ single-payer proposal during the campaign said implementing the plan would increase federal expenditures by $32 trillion over 10 years.