Donald Trump's campaign manager arrested on battery charge following claims he bruised reporter's arm
Florida police have charged Donald Trump's campaign manager with misdemeanor battery in an incident with a reporter earlier this month.
Corey Lewandowski turned himself in to police, where he was issued with a notice to appear before a judge on May 4.
In a second piece of bad news for Mr Trump, Wisconsin governor Scott Walker endorsed his rival Ted Cruz in the Republican race for the party's nomination.
A surveillance video released by the police appears to show Lewandowski grabbing a woman reporter for Breitbart News as she tried to ask Mr Trump a question during a March 8 campaign event.
The reporter filed a complaint and posted pictures of her bruised arm. That incident and past Mr Trump remarks about women are hurting his support among female voters.
The Trump campaign said Lewandowski "is absolutely innocent of this charge".
Mr Walker said his endorsement was not part of mainstream Republicans' drive to block front-running Mr Trump but support for "a strong new leader".
The Wisconsin governor, who was briefly in the race for the Republican nomination, announced his support for Mr Cruz and said he is "in the best position by far to both win the nomination of the Republican Party and then go on to defeat Hillary Clinton in the fall".
Mr Trump planned to make his first campaign appearance in Wisconsin before joining Ohio governor John Kasich and Mr Cruz for a CNN interview.
It is unclear how much Mr Walker's endorsement will help Mr Cruz. The governor's approval rating has not cracked 40% in more than a year.
Wisconsin has 42 delegates, with 18 going to the state-wide winner and 24 divided among the winners in each of the state's eight congressional districts. Mr Trump heads into Wisconsin with 739 delegates to Mr Cruz's 465. Kasich lags behind with 143. It takes 1,237 to assure the nomination.