Trump keeps pushing racial boundaries.
Analysis by Gary O'Donoghue, BBC Washington Correspondent
Telling people of colour to go back to where they came from cannot be regarded as anything other than a blatant evocation of a well-worn trope of racist language and sentiment that's as old as the hills.
But usually politicians who want to play the race card reach for the "dog whistle" - a political nudge and a wink that tells their supporters that they share their views that cannot easily be voiced in a liberal democracy without alienating people whose support they will need.
President Trump, however, has pushed the boundaries on racially charged language ever since he became a candidate.
Remember how Mexicans were Rapists and Drug dealers, how there were "good people" on both sides of the argument when white supremacists marched in Charlottesville, and how the President didn't see why America should allow more people in from "shithole" countries in Africa.
So what is his strategy? Keeping his core support fired up is unquestionably part of it. And exploiting divisions within Democratic ranks which have had racial overtones in recent days is another reason for his actions.
But in many ways, we should not be surprised by this President ratcheting up the political heat in this particular way.
After all, it's a short intellectual step from the economic nationalism encapsulated in the idea of America First, to a more thorough-going nationalism that sees a threat from the enemy within.
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