That psychotic comment is a new low, even by King’s ignominious standards, but it shouldn’t surprise anyone. During an appearance on MSNBC in July 2016, King questioned what nonwhite “subgroups” have contributed to history. His entire quote from that appalling exchange was:

This whole ‘old white people’ business does get a little tired, Charlie. I’d ask you to go back through history and figure out where are these contributions that have been made by these other categories of people that you are talking about? Where did any other subgroup of people contribute more to civilization?

Then there’s his love affair with right-wing, anti-immigrant, European nationalists like Wilders, Austrian presidential candidate Norbert Hofer, France’s Marine Le Pen, and Germany’s Fruake Petry, among others, whom Think Progress appropriately described as “anti-immigrant demagogues.”

King is quickly establishing his credentials with elite white nationalists like former KKK grand wizard and Trump supporter David Duke, who tweeted praise for the Iowa congressman's latest outburst.

But how far is this Republican cultural crusader and open white nationalist willing to go to prevent what he calls “cultural suicide by demographic transformation?” That remains to be seen, but if Sunday’s tweet is any indication, he’s ramping up his racist rhetoric, stepping out from the shadows, and whipping out that great, white dog whistle that’s becoming a frighteningly common fixture in the U.S. mainstream political landscape these days. The real question is how long are Iowans—and his congressional colleagues—going to let him get away with it?