Donald Trump's campaign manager Corey Lewandowski will not be prosecuted for reporter battery

A Florida prosecutor has decided not to press charges for battery against Donald Trump's campaign manager Corey Lewandowski for grabbing the arm of a political reporter at a campaign news conference, according to sources.

Palm Beach County State Attorney David Aronberg is expected to announce the decision soon, Politico reported. He was reportedly attempting to arrange a deal in which Lewandowski could duck a battery charge if he publicly apologised to former Breitbart reporter Michelle Fields.

The reporter had agreed to that, but it was not immediately clear if that arrangement had worked out. Fields herself appeared to be in the dark.

"For those asking, office of prosecutor asked two weeks ago if I'd be OK with an apology from Corey. I said ya but haven't heard back about it," Fields tweeted.

She seemed annoyed that the press found out about Aronberg's decision before she was informed. "Guess they decided to leak to reporters first," she tweeted. "Ugly."

The confrontation occurred at a campaign event in early March in Jupiter, Florida, where Trump held a news conference. As Fields walked alongside Trump, asking him questions, Lewandowski suddenly appeared to grab her arm and yank her away from the candidate. In a previous incident, Lewandowski had been captured on video apparently grabbing the collar of a protestor.

Fields filed a complaint against Lewandowski with police and tweeted about it. Lewandowski denied the confrontation in a tweet and insisted that he had never even met Fields. But video from Trump's own campaign security cameras, released by the local police department, clearly shows that Lewandowski grabbed Fields.

Police charged Lewandowski with misdemeanour battery. But while police have a low "probable cause" threshold to meet, there is "a higher standard to go forward with a prosecution."

Trump defended his campaign manager and said that it was Fields who was "grabbing at me," and that Lewandowski was protecting him. Trump also said that it was possible Fields' pen held a "little bomb."

Fields quit her job at Breitbart, saying that the conservative online new site, which supports Trump's policies, did not stand behind her. Other colleagues also quit in protest. She is still considering a suit against Lewandowski for defamation.