President Barack Obama has appealed for calm on the streets of Missouri after days of clashes between police and protesters.
The tensions follow the fatal shooting of a black teenager by a police officer in the St. Louis suburb of Ferguson.
President Obama said there was "no excuse" for "police to use excessive force against peaceful protesters" or for "violence against police".
ITV News' Washington Correspondent Robert Moore reports:
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Rain will spread eastwards across southern areas tonight. Clear and frosty in the north.
Political leaders will go head-to-head at ITV's studios in MediaCityUK in Salford, ITV has confirmed, as the set for the event is unveiled.
More than 100 people claiming to represent working people across Britain have signed a letter backing Labour in the general election.