Report from Robert Moore, Washington Correspondent, ITV Newss

It was always a narrow line separating Donald Trump's raucous political campaign and utter chaos.

This morning that line appears to have been crossed.

Trump campaign plagued by reports of violence from supporters

Amid violent and tumultuous scenes between rival pro and anti-Trump camps, a rally in Chicago had to be cancelled.

Another in St Louis descended into farce with dozens of protesters being ejected.

Trump stands accused of directly encouraging the scuffles by using incendiary language and revelling in the politics of hate and division.

Normally this would - at a stroke - destroy a politician's prospects.

But Trump is different. A new, angry, alienated coalition is gathering around him. These supporters are unfazed by the antics and the provocations.We are seeing the ugly side of American politics.

Not the politics of hope. But the politics of fear.

Not the aspirational, optimistic language we associate with America. But the dark, bitter language of a demagogue playing to a crowd's worst instincts.