The war of words between presumptive presidential candidates spilled over Monday to their designated attack dogs, with Donald Trump surrogate Scott Brown getting into a bare-knuckles street fight with Sen. Elizabeth Warren, calling on her to take a DNA test to prove her Native American heritage after she took shots at... Trump's hats.

Brown – the ex-Massachusetts senator who lost his seat to Warren in 2012 – made the DNA remark on a conference call set up by the Republican National Committee on Monday afternoon, hours after Warren appeared with likely Democratic presidential nominee Hillary Clinton in Ohio and slammed Trump. Warren, whom Trump regularly calls “goofy Elizabeth Warren,” used the same terminology to jab back at the billionaire mogul.

“Donald Trump says he’ll ‘Make America Great Again,’” Warren said. “It’s right there. It’s stamped on the front of his goofy hat. You wanna see goofy? Look at him in that hat.”

Warren also called Trump “a small, insecure, money grubber” and “a nasty man” during her introduction of Clinton.

Trump, who has frequently referred to himself as an expert counter-puncher, called an MSNBC reporter soon after and unloaded on Warren.

Trump told the reporter he hadn’t seen Warren’s speech but was informed of her comments. He then proceeded to mock Warren’s claim of being 1/32nd Cherokee, again referring to Warren as “Pocahontas.”

“She made up her heritage, which I think is racist. I think she’s a racist actually because what she did was very racist,” Trump was quoted as saying. “She’s been totally unable to prove she’s Native American and yet used that to advance her career.”

Trump told the reporter he hoped Warren was selected as Clinton’s running mate, saying he was ready to turn “both barrels” on the pair.

The controversy surrounding Warren’s heritage entered the national spotlight during the 2012 Massachusetts senate race when Brown levelled Trump-like charges at Warren, accusing her of lying about her ancestry in the name of career advancement. Warren has said she heard about her Indian lineage from family stories.

Brown returned to that line of attack Monday after Trump took his shots, with the two forming a tag-team approach similar to the 1-2 punch adopted by Warren and Clinton earlier in the day.

Aside from proposing a DNA test, Brown said Clinton “is considering making someone vice president who has very serious character flaws when it comes to honesty and credibility” in terms of her background.

The style of rhetoric from Brown and Trump was in stark contrast to a more moderate, but still-scathing statement sent by the Trump campaign attacking Warren as “a turncoat” for supporting Clinton in light of Clinton’s ties to Wall Street. Clinton's introduction by Warren, a regular and vocal critic of Wall Street, was a “sad attempt at pandering” to Sen. Bernie Sanders’ wing of the party, the statement said.

Clinton was far less fiery in her remarks in Cincinnati on Monday, but she did give Warren’s verbal shots at Trump a nod of approval.

“I just love how she gets under Donald Trump’s skin,” Clinton said.

Monday's heated exchanges were the latest examples of Clinton and Trump trading insults as the general election campaign for both candidates begins in earnest.

Referencing Britain's vote to leave the European Union, Trump questioned Clinton's judgement on Friday in a tweet, also using one of his favorite nicknames for the former Secretary of State.

"Crooked Hillary called it totally wrong on BREXIT - she went with Obama - and now she is saying we need her to lead. She would be a disaster," Trump tweeted.

Clinton, meanwhile, has mostly stuck to more civil rebukes, though she often calls Trump out as "reckless."

“Every day, we see how reckless and careless Trump is," Clinton said during an event last week. "He’s proud of it. Well – that’s his choice. Except when he’s asking to be our President. Then it’s our choice."

Trump on June 22 devoted an entire speech to criticizing Clinton's entire career, quoting liberally from an upcoming book by a Secret Service agent who railed against Clinton's temperament as well as hitting Clinton on her private e-mail server, The Clinton Foundation and Benghazi.

In that speech, Trump called Clinton "the most corrupt person ever to seek the presidency."