Trump didn’t backtrack on pledge: Aide

Trump spokeswoman on campaign manager charges
Trump spokeswoman on campaign manager charges

The Trump campaign asserted on Wednesday that Donald Trump did not backtrack on a pledge to support the GOP presidential nominee if the party did not choose him.

Trump campaign spokesperson Katrina Pierson told CNBC the GOP front-runner is in fact abiding by the terms of his earlier promise, in which he said he would lend his support so long as he felt the party was treating him fairly.

Pierson said Republicans are not treating him fairly.

"You have an entire anti-Trump movement consisting of party elites that are out there trying to stop Trump from winning the nomination, and even joining with Democrats to try to make that happen," she said on "Squawk on the Street."

Trump drops pledge to back Republican presidential nominee other than himself

Former GOP presidential candidates Mitt Romney and Sen. John McCain have denounced Trump, and prominent Republicans have organized a political action committee dedicated to stopping him.

During a town hall meeting on Tuesday, Trump told CNN he would no longer support another GOP candidate. The comment came in the wake of escalating personal attacks between his campaign and supporters of Texas Sen. Ted Cruz.

Earlier Tuesday, Cruz also said he would not necessarily support the party's nominee. "I'm not in the habit of supporting someone who attacks my wife and my family," he told CNN.

Asked about the pledge, Ohio Gov. John Kasich told CNN: "All of us shouldn't even have answered that question."

Pierson also said Trump will stand by campaign manager Corey Lewandowski, who was charged with simple assault on a reporter.

Police in Jupiter, Florida, said Lewandowski surrendered Tuesday morning to face a misdemeanor charge of battery.

A surveillance video released by the police appears to show Lewandowski grabbing Breitbart News reporter Michelle Fields as she tried to ask Trump a question during a March 8 campaign event.

Pierson said the footage clearly shows Lewandowski did not assault Fields. She added that the Trump campaign did not fire Lewandowski "simply because you don't ruin a man's career just because your opposition wants you to."

— The Associated Press contributed to this story.