The president claimed, without giving evidence, that the protesters were “paid” agitators, that the Los Angeles police asked for the National Guard, and that swaths of the city were under gang control.

They are trying to strike a careful balance on issues where Republicans have held a political advantage in recent years.

President Donald Trump’s deployment of military troops to California is forcing Democrats back onto politically perilous turf, as they look for ways to condemn Trump’s actions without being drawn into a broad debate over immigration or tying themselves to the chaotic scenes emerging from Los Angeles.