GOP presidential front-runner Donald Trump Donald John TrumpObama calls on Senate not to fill Ginsburg's vacancy until after election Planned Parenthood: 'The fate of our rights' depends on Ginsburg replacement Progressive group to spend M in ad campaign on Supreme Court vacancy MORE on Monday called Sen. Elizabeth Warren Elizabeth WarrenBiden's fiscal program: What is the likely market impact? Warren, Schumer introduce plan for next president to cancel ,000 in student debt The Hill's 12:30 Report - Presented by Facebook - Don't expect a government check anytime soon MORE (D-Mass.) an “Indian,” mocking her for an old claim of Native-American ancestry.

Earlier in the day, Warren went on a Twitter rant against Trump, calling him a "loser" and a "serious threat" to the United States.

“You mean the Indian?” Trump asked when a reporter inquired about the senator's comments during a press conference in Washington, D.C. “Who’s that? The Indian?”

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Trump accused Warren of inflaming tensions between everyday Americans by attacking the legitimacy of his White House run.

“The problem with this country right now is it’s so divided,” he said. "People like Elizabeth Warren really have to get their act together because it’s going to stay divided."

“That includes Hillary,” Trump continued. "And that probably includes me."

Warren met with controversy during her 2012 Senate campaign when reports emerged that Harvard Law School once touted her alleged Cherokee and Delaware ancestors as proof of its faculty’s diversity.