Healthcare and gun violence were both major talking points in the debate

Bernie Sanders criticised Hillary Clinton for taking $600,000 worth of speaking fees from Goldman Sachs in their most aggressive candidacy debate yet.

Sanders twice questioned her commitment to policing Wall Street's excesses while Clinton, who leads the race to be come the Democrat party's presidential candidate, blasted him for wanting to raise taxes.

At times, the two front runners shouted over each other at the Gaillard Center in Charleston, South Carolina, in their final debate before the Iowa caucuses.

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Bernie Sanders (right) criticised Hillary Clinton (left) for taking $600,000 worth of speaking fees from Goldman Sachs in their final debate before the Iowa caucuses

Sanders (right) twice questioned her commitment to policing Wall Street's excesses while Clinton (left), who blasted him for wanting to raise taxes

Some of the crowd booed Sanders, who twice brought up Clinton's receipt of lucrative speaking fees since leaving her post as secretary of state in early 2013.

They also butted heads over health care, taxes and gun violence - which have all emerged as central points in the race.

Just hours before the debate, Sanders announced a proposal that would create a 'Medicare for all' health system funded by higher taxes on Middle Class families and the wealthy.

His voice rising at times, Sanders made a rousing case for the expansion of the government, universal health care, free college tuition and paid leave for workers with families.

He said: 'A little bit more in taxes, do away with private health insurance premiums...It's a pretty good deal.'

But Clinton warned that even reopening the medical debate debate put President Barack Obama's healthcare law at risk.

Some of the crowd booed Sanders (pictured), who twice brought up Clinton's receipt of lucrative speaking fees since leaving her post as secretary of state in early 2013

Clinton (left) and Sanders (right) butted heads over health care, taxes and gun violence - which have all emerged as central points in the race

She blasted Sanders' so called 'single payer plan' and accused him of making things up as he went along.

She said: 'When we're talking about health care, the details really matter.'

I'm the only candidate standing here tonight who has said I will not raise taxes on the middle class Hillary Clinton

Clinton claimed her policies were superior and the American people would know exactly how her plans would be implemented and paid for.

She said: 'I'm the only candidate standing here tonight who has said I will not raise taxes on the middle class.

'I want to raise incomes, not taxes, and I'm going to do everything I can to make sure that the wealthy pay for debt free tuition, for child care, for paid family leave.'

Clinton made an all-purpose case for her leadership and her ability win the White House, saying: 'We need a president who can do all aspects of the job.'

She questioned Sanders on why he reversed his position on a 2005 bill that granted gun manufacturers immunity from lawsuits. She went on to list a series of provision that suggested Sanders stood in line with the National Rifle Association.

Clinton (left) claimed her policies were superior and the American people would know exactly how her plans would be implemented and paid for

At times, the two leading Democratic presidential candidates shouted over each other at the Gaillard Center (pictured) in Charleston, South Carolina

Sanders claimed she was being 'very disingenuous' and pointed to his lifetime rating of 'D-minus' from the National Rifle Association.

Throughout the night, Clinton embraced Obama's legacy, assuming that the president's popularity could help her with primary voters.

She repeatedly defended the Affordable Care Act and said Sanders' approach would reopen a debate that might come back to haunt Democrats.

She said: 'I do not to want see the Republicans repeal it, and I don't to want see us start over again with a contentious debate.'

Clinton's case for tougher gun control also aimed to put her on the same side as Obama, who recently signed executive orders aimed at addressing a series of recent mass shootings.

The exchanges were a far cry from the first debate of their campaign, when Sanders famously refused to attack Clinton for her use of a private email account and server at the State Department.

Maryland governor Martin O'Malley, the third candidate in the debate, barely qualified to appear on the debate stage and, at times, struggled to get a word in over Sanders (right) and Clinton

The exchanges last night were a far cry from the first debate of their campaign, when Sanders famously refused to attack Clinton for her use of a private email account and server at the State Department

Meanwhile Maryland governor Martin O'Malley, the third candidate in the debate, barely qualified to appear on the debate stage and, at times, struggled to get a word in as Sanders and Clinton jousted on the issues.

As the debate's moderator headed into the first commercial break, O'Malley asked, 'Just ten seconds?' to no avail.