"a sliver over 50% of a public to successfully endorse a government policy"

You don't need anywhere near that. In fact Hitler came to power on the basis of 37% of the vote, and a flawed electoral system. That's the kind of percentage that people like that can get in lots of elections today, and it can be enough.

In 1928 the Nazis got 3%; by 1930m it was 17%, and by 1932 it was the 37% that did the trick.

Pretty frightening, when you think of it. We think we're safe...

Here's a YouTube clip of Leni Riefenstahl's Triumph of the Will.