GOP presidential front-runner Donald TrumpDonald TrumpIran claims U.S. to lift all oil sanctions but State Department says 'nothing is agreed' Ivanka Trump, Kushner distance themselves from Trump claims on election: CNN Overnight Defense: Joint Chiefs chairman clashes with GOP on critical race theory | House bill introduced to overhaul military justice system as sexual assault reform builds momentum MORE promised late Thursday night that he would no longer curse on the campaign trail.

“I won’t use foul language,” he told supporters during a rally in Baton Rouge, La.

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“I’m just not going to do it. I’ll never do it again, actually, and I’ll never even copy what somebody asks me to say.”

Trump’s rivals for the Republican presidential nomination have criticized his public profanity as crass and undignified.

“I’m not sure a lot of voters are excited about having a president who, when he gets rattled or gets upset, he begins cursing and yelling vulgarities,” rival candidate Ted CruzRafael (Ted) Edward CruzNew Jersey governor tweaks Cruz on Cancun over moving truck quip Hirono tells Ted Cruz to stop 'mansplaining' Senate Republicans: Newly proposed ATF rules could pave way for national gun registry MORE said in Fort Mill, S.C., late Thursday evening, according to MSNBC.

“You turn on the TV and you see a leading presidential candidate saying profanity from a stage,” Marco RubioMarco Antonio RubioOvernight Defense: Joint Chiefs warn against sweeping reform to military justice system | Senate panel plans July briefing on war authorization repeal | National Guard may have 'training issues' if not reimbursed Senate panel plans July briefing on war authorization repeal Rising violent crime poses new challenge for White House MORE, another GOP contender, said the same day in Okatie, S.C. "Profanity from a stage. All these things undermine what we teach our children.”

Trump has repeatedly vowed he will “bomb the shit” out of the Islamic State in Iraq and Syria as president. He recently sparked outrage for echoing a supporter who called Cruz a “pussy."