Senator Bernie Sanders is relaunching his push for a government-funded healthcare system, 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.

While defending Obamacare – which Republicans unsuccessfully tried to dismantle in July – the Vermont independent declared 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.

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.

“Medicare-for-all ...will be saving middle-class families substantial sums of money, and it will be guaranteeing health care to every man, woman, and child in this country,” Mr Sanders, who caucuses with the Democrats, told CNN.

Mr Sanders will soon be introducing a bill in the Senate that would create this system, a major plank of his 2016 presidential campaign, even if he knows it is unlikely to pass in the current political climate.

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.

“Look, I have no illusions that under a Republican Senate and a very right-wing House and an extremely right-wing president of the United States, that suddenly we're going to see a Medicare-for-all, single-payer passed,” Mr Sanders recently told NPR. “You're not going to see it. That's obvious.”

But he said the point of the bill is to force conversation about the idea.

“Senator Sanders has always believed that health care must be recognized as a right, not a privilege,” office spokesperson Daniel McLean told the Independent. “Like every other major country on Earth, every man, woman and child in our country should be able to access the health care they need regardless of their income.”

The concept of a single-payer system is becoming increasingly popular in the Democratic party – senators including Cory Booker, Kirsten Gillibrand and Kamala Harris have expressed some support, and, for the first time, a majority of Democrats in the House of Representatives have now signed on to the single-payer bill that Congressman John Conyers has been introducing regularly for more than 10 years.

However, experts fear that supporting a single-payer programme could become a litmus test for Democrats, meaning members either support the bill or progressive political action committees, or PACs, try to prevent them from getting reelected.

In pictures: President Donald Trump on tour Show all 39 1 /39 In pictures: President Donald Trump on tour In pictures: President Donald Trump on tour 20 May 2017 US President Donald Trump and Saudi Arabia's King Salman bin Abdulaziz al-Saud arriving for a reception ahead of a banquet at Murabba Palace in Riyadh Getty Images In pictures: President Donald Trump on tour 20 May 2017 US President Donald Trump, accompanied by First Lady Melania Trump, and Saudi Arabia's King Salman bin Abdulaziz al-Saud being welcomed at Murabba Palace in Riyadh Getty Images In pictures: President Donald Trump on tour 20 May 2017 US President Donald J. Trump with King of Saudi Arabia Salman bin Abdulaziz Al Saud during a welcome ceremony with traditional sword dancers at Murabba Palace, in Riyadh, Saudi Arabia EPA In pictures: President Donald Trump on tour 20 May 2017 King of Saudi Arabia Salman bin Abdulaziz Al Saud with US President Donald J. 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“Any Democrat worth their salt that doesn't unequivocally say Medicare-for-all is the way to go? To me, there's something wrong with them,” Nina Turner, president of Mr Sanders' Our Revolution PAC, told Politico. “We're not going to accept no more hemming and hawing.”

While the progressive, and arguably most energetic, wing of the party has gotten behind the single-payer idea, it still remains a divisive issue for moderate Democrats. The proposal was notably excluded from Democratic leaders’ new economic agenda that was unveiled last month.

The party has been desperate to regain its mojo following its defeat last November, when it failed to win a majority in the Senate and Donald Trump triumphed over Democratic nominee Hillary Clinton.

It will be a challenge for Democrats to retake a majority in both the House of Representatives and Senate during the 2018 midterm elections. The party needs a net gain of 24 to have a majority in the 435-member House. And while they only need a net gain of three seats in the 100-member Senate, they are also defending 25 seats – 10 of which are in states that Mr Trump won.

“Single-payer healthcare as an issue is a worthy debate for the Democrats to be having,” said Jim Kessler, the senior vice president for policy for Third Way, a centrist think tank. “But it’s a huge mistake to make it a litmus test for Democrats at this point.”

Instead of pushing for a healthcare system overhaul in the US that Mr Trump will reject, some of suggested, all efforts should be focused on improving Obamacare – otherwise known as the Affordable Care Act – which still remains under attack by the President.

At the end of July, one vote prevented the Senate’s Republican leadership from passing a bill that would have repealed major provisions of former President Barack Obama's healthcare law.

“We are one lousy election in November 2018 away from losing Obamacare,” Mr Kessler said.

“The stronger that Obamacare is, the great likelihood it will survive the next assault.”

Republican members of Congress, as well as Mr Trump, campaigned for years on repealing and replacing Obamacare, which they say has driven up premiums and forced consumers to buy insurance they do not want or cannot afford.

In June, when asked why Democrats aren't countering Republicans with a single-payer plan, House Democratic Leader Nancy Pelosi said “it isn't helpful to tinkle all over the Affordable Care Act right now."