GOP presidential front-runner Donald TrumpDonald John TrumpHouse expected to vote on omnibus Thursday afternoon House passes 'right to try' drug bill Spending bill rejects Trump’s proposed EPA cut 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.

“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 CruzTrump can save Republicans and restore sanity to California in 2018 Cruz says Cambridge Analytica assured him its practices were legal Dem battling Cruz in Texas: ‘I can understand how people think this is crazy’ 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 RubioRussia leak raises questions about staff undermining Trump House members urge Senate to confirm Trump's NASA nominee Rubio: McCabe 'should've been allowed to finish through the weekend' 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."