Trump campaign manager won't be prosecuted for assault

Republican presidential candidate Donald Trump's campaign manager will not be prosecuted on a charge of misdemeanour battery over allegations he grabbed the arm of a reporter.

Trump campaign social media director Dan Scavino posted on his Facebook page late Wednesday night that the charge would not be pressed against Corey Lewandowski, Fox News reported on Thursday.

The decision not to prosecute Lewandowski was first reported by political-journalism organisation, Politico.

Palm Beach County State Attorney David Aronberg was scheduled to formally announce his decision on Thursday afternoon.

The incident occurred after a March 8 press conference at the Trump National Golf Club in Jupiter, Florida, where Lewandowski was accused by Michelle Fields, a reporter for Breitbart at the time, of grabbing her arm as she asked the Republican front-runner a question.

Lewandowski initially denied the incident had taken place.

Fields told Fox News that she is planning to pursue a civil case against Lewandowski for defamation.

Trump has staunchly defended his campaign manager after he was charged, as the business mogul suggested the reporter could have been perceived as a threat.