Sen. Bernie Sanders Bernie SandersOutrage erupts over Breonna Taylor grand jury ruling Dimon: Wealth tax 'almost impossible to do' Grand jury charges no officers in Breonna Taylor death MORE (I-Vt.) is firing back at businessman Donald Trump Donald John TrumpBiden on Trump's refusal to commit to peaceful transfer of power: 'What country are we in?' Romney: 'Unthinkable and unacceptable' to not commit to peaceful transition of power Two Louisville police officers shot amid Breonna Taylor grand jury protests MORE after the GOP front-runner suggested Sanders wants to increase tax rates to 90 percent.

"It appears that Donald Trump, a pathological liar, simply cannot control himself. He lies, lies and lies again," Sanders, who is running for the Democratic nomination, said in a statement Wednesday. "Today, he repeated his lie that I want to raise taxes to 90 percent. Totally untrue."

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Sanders's comments come after Trump told supporters at a South Carolina campaign stop that "this guy wants to raise your taxes to 90 percent" and called the Vermont senator a "total disaster."

It's not the first time Trump has made the comment about Sanders. PolitiFact previously fact checked Trump's remarks in October, rating it as "pants on fire," or false.

The two presidential hopefuls have been trading rhetorical barbs while also suggesting they could be able to poach each others supporters.

Sanders's canvassers are being instructed to sell their candidate to Trump backers, according to a copy of a campaign script obtained by MSNBC.

Sanders had made increasing taxes on wealthy Americans and large corporations central to both his presidential campaign and his time in the Senate, but he's repeatedly denied Trump's accusations.

He added on Wednesday that "billionaires like Trump should pay their fair share of taxes."

"It is grossly unfair that there are millionaires in this country who take advantage of all kinds of loopholes and end up paying an effective tax rate lower than a middle-class worker," he said.