Donald Trump Jr. mocked Sen. Elizabeth Warren (D-MA) on Monday — declaring that if she cannot take the heat, she should “get out of the teepee!” — after the presidential hopeful expressed disappointment in Sen. Bernie Sanders’ (I-VT) campaign, which reportedly urged volunteers to tout anti-Warren talking points.

“If @ewarren can’t take the heat she should get out of the teepee!” Trump wrote, a reference to the Democrat candidate’s past false claims of Native American heritage:

If @ewarren can’t take the heat she should get out of the teepee! https://t.co/GqQkookRVu — Donald Trump Jr. (@DonaldJTrumpJr) January 13, 2020

Warren on Sunday told reporters in Iowa that she was “disappointed” to hear that the Sanders campaign was encouraging volunteers to use talking points to discourage voters from supporting her. One of the talking points, according to Politico, urged volunteers to note that Warren is “bringing no new bases into the Democratic Party.”

“I was disappointed to hear that Bernie is sending his volunteers out to trash me,” Warren told reporters.“Bernie knows me and has known me for a long time. He knows who I am, where I come from, what I have worked on and fought for.”

“Democrats need to unite our party, and that means pulling in all parts of the Democratic coalition,” she continued, refraining from taking an equal shot at her ideological ally.

“I hope Bernie reconsiders and turns his campaign in a different direction,” she added:

Warren hits back: “I was disappointed to hear that Bernie is sending his volunteers out to trash me. Bernie knows me and has known me for a long time…I hope bernie reconsiders and turns his campaign in a different direction.” Also notes the “factionalism” caused by 2016 https://t.co/ER0Vm6sgJS pic.twitter.com/N8prZdeZk9 — Alex Thompson (@AlxThomp) January 12, 2020

The two will appear on the same debate stage Tuesday night, alongside Joe Biden (D), Pete Buttigieg (D), Sen. Amy Klobuchar (D-MN), and Tom Steyer (D).