Donald Trump has backtracked on his much-ballyhooed pledge to support the eventual Republican nominee as he deals with swirling controversy after his campaign manager was charged with assaulting a reporter.

In a television town hall in Milwaukee with CNN on Tuesday night, Trump insisted he had been “treated very unfairly” by the Republican National Committee and the establishment and revoked the commitment he signed in September.

Although the Republican frontrunner previously hinted that he might do so, saying the RNC was “in default”, he had never explicitly revoked his commitment until Tuesday.

The statement came as Trump stood by Corey Lewandowski, his embattled campaign manager, who was captured on tape Error! Hyperlink reference not valid.for the right-wing website Breitbart after a press conference.

Trump suggested that the reporter, who had been screened by the secret service in order to be allowed in the candidate’s vicinity, may have been carrying a bomb.