gabe tierrez has this report for us. >> reporter: this weekend the anger boiled over, in tucson a protester in a white hood escorted out by police, and another one behind him repeatedly bunched and kicked by spoke with nbc's jacob rascon. >> you may get beat to death inside of a rally. >> but it's this video that is raising even more questions, trump's campaign manager appears to grab the collar of another protest who is yanked away by security. >> security at the arena, the police were a little lax and he had signs, they had signs up in thth area that were horrendous. i will give him credit. >> last week a reporter from the conservative website filed a police complaint accusing him of assault butt he has not been charged. the long time gop operative went to work as a new hampshire police officer. >> it's unprecedented for a campaign manager to be out in the crowd, being involved in security. >> ted cruz campaigning in arizona. >> there is now only one campaign in a position to beat republican nomination. >> polls show he trails trump there. john kasich betting onn a contested convention. >

>> gabe guan tianlang tierrez, thank you. >>> trump is casting blame on the democrats specifically bernie sanders who in response has flatout called trump a liar. meanwhile, hillary clinton's latest attack has backfired a bit. we get more on all of that from nbc's kristen welker. >> reporter: donald trump calling for the arrest of violent protesters at his rally. now saying democrats are orchestrating them. laying blame directly at senator bernie sanders. all over the place. they were made by bernie sanders people. >> reporter: sanders dismissing trump's claim. >> we have never never once called anybody to do anything like that. the truth is, this guy really is a path logical liar. >> reporter: trump threatening retaliation, tweeting bernie sanders is lying when he says his disrupters aren't told to go to my events. be careful, bernie, or my supporters will go to yours. while some sanders' supporters denied getting violent. it's the other way around. >> i have been getting death threats since the trump rally. it came with the territory. these are the type of people that i support -- that