News of riots and disturbances leading to the cancellation of a Trump rally is not good news for his campaign, yet it may as he says reflect the pent up anger on both sides at what is perceived to be failure of governance in Washington. Both the Republican and Democrat establishments are in trouble, although the Trump effect is much the more dramatic. Yet Sanders, having apparently been overwhelmed by the Clinton juggernaut, has bounced back with a shock win in Michigan. He might just pull it off again in the rust belt states. There is even talk of Florida going his way. This is unlikely, although if it happened it would be a hit from which Clinton might not recover.
Back to Trump. A President who provokes riots in his own country is unlikely to be, when it comes down to the wire, the choice of Americans for the White House. Obama has called on all sides to stay calm. Trump’s lot need to cool it if they want to retain momentum. Riots are not political theatre.