Democratic Presidential candidate Bernie Sanders speaks during a rally in Boston in October. (Darren McCollester/Getty Images)

Hours after being called a “wacko” by Donald Trump, Democratic presidential hopeful Bernie Sanders fired back Monday at the Republican front-runner, saying he was pushing “pathetic policies” designed to benefit billionaires such as himself at the expense of misguided working-class voters who support him.

Sanders and Trump have been engaged in an escalating war of words since Sunday, when the Vermont senator asserted during an appearance on “Face the Nation” that he is better-positioned than Trump to represent the economic interests of some the real estate mogul’s followers.

Trump opposes raising the minimum wage and supports some tax cuts for higher-income earners, positions that Sanders argued during the CBS program are contrary to the interests of Trump’s lower- and middle-class supporters. Sanders, a self-described democratic socialist, has made that argument before, but it gained greater prominence with the Sunday show exposure.

[In Nevada, Sanders mocks Republicans for running to casino mogul for a financial lift]

On Monday morning, Trump took to Twitter to argue that if anyone is going to poach another candidate’s supporters, it’s him.

“Strange, but I see wacko Bernie Sanders’ allies coming over to me because I’m lowering taxes, while he will double and triple them — a disaster!” Trump tweeted.

Trump echoed those sentiments during a rally Monday night in Nashua, N.H., where he again called Sanders a “wacko” and warned that Sanders’s election would mean “massive, massive, massive tax increases” because he wants to “give everyone everything free.”

“I don’t think there’s too many Bernie Sanders people here,” Trump said, surveying his crowd.

[Trump’s latest targets: New Hampshire’s largest paper and its favorite candidate, Christie]

Sanders, who is seeking to upset Hillary Clinton in his bid for the Democratic nomination, responded following a rally of his own Monday night in North Las Vegas.

Being called wacko by a pathological liar like Mr. Trump makes me think he is getting nervous that the American people are catching on to his pathetic policies, which include giving hundreds of billions of dollars in tax breaks to billionaires like himself while refusing to raise the $7.25 an hour minimum wage,” Sanders said in comments relayed through a spokesman.

Sanders had previously called Trump a “pathological liar,” citing his debunked claim that thousands of Muslims in New Jersey were shown on television cheering after 9/11.

In remarks at his rally Sunday night, Sanders also took aim at Trump, citing his proposals to temporarily ban all Muslims from coming into the country and to deport millions of undocumented immigrants.

“There are people out there, Donald Trump and others, who are attempting to do what demagogues have always done, and that is instead of bringing people together to address and solve the real problems that we face, what they try to do is tap the anger and the frustration that people are feeling and then divide us up,” Sanders told a crowd estimated at 3,200 people. “So we have a message to Trump and all the others out there who want to divide us up: No, we’re not going to hate Latinos, we’re not going to hate Muslims, we are going to stand together.”

The balance of Sanders’s speech was devoted to issues he’s been pushing for months, including addressing income inequality, reforming a “broken” criminal justice system and combating climate change.

His appearance at a North Las Vegas high school wrapped up a two-day swing through Nevada, which holds its Democratic caucuses on Feb. 20, shortly after the first two nominating contests in Iowa and New Hampshire.