A widely held tenet of the current conventional wisdom is that while President Trump might not be popular overall, he has a high floor on his support. But the theory isn’t supported by the evidence. To the contrary, Trump’s base seems to be eroding. There’s been a considerable decline in the number of Americans who strongly approve of Trump, from a peak of around 30 percent in February to just 21 or 22 percent of the electorate now. Far from having unconditional love from his base, Trump has already lost almost a third of his strong support. By Nate Silver.