Trump says campaign manager didn't yank protester by his shirt, it was some other guy...who was also on the Trump payroll.
When a protester was yanked by his collar at a Trump rally, the incident was caught on camera and seemed to implicate Corey Lewandowski—Trump's campaign manager, who has already been accused of assaulting a female journalist. Naturally, the Trump campaign rushed to defend Lewandowski from a second accusation of violence on the job (among other allegations that concern even Trump staffers), and blamed it on the man next to him in a dark pullover. That man has since been revealed to be a security staffer for the Trump campaign.
Trump himself said that the incident was primarily the protester's fault for having a "horrendous" sign with profanity on it, and that although he gave Lewandowski credit for having "spirit," he didn't touch him. A Trump spokesperson, Hope Hicks, declined to say why Trump's campaign manager was interacting with protesters, although Trump blamed it on lax policing in an interview with ABC (below). Just to be clear, this was separate from the other, much more violent incident at the same rally in Arizona: