I understand that in the 1930s, Hitler and other party members began instituting a single party state from the bones of the Weimar Republic. But in the run up to the dictatorship, to what degree do historians describe the change as democratic? Were there particular key points, like when Hitler gained the chancellorship and Notverordnungen powers, that "flipped the switch" on the government? Or were there still in place the mechanism(s) of the German democracy? From what I understand, the Weimar Constitution was still in place up until the end of the war in Europe.
I don't mean for this to be quite so broad. I understand that looking at the history of democracy, there is the real problem that democracy is a kind of nebulous concept. And, of course, I don't want to imply that just because Germany was a democracy before (and even during some) of Hitler's reign, that makes the whole of the German polity a special brand of villainy. I've read Mann's The Dark Side of Democracy, and recognize that making the world safe for democracy is much more prickly than Woodrow Wilson let on (to say the least).
The Nazi rise to power was almost wholly undemocratic, and broke completely with the principles that encompass a democracy.
The period immediately prior to and after the election of 1933 is referred to as the Machtergreifung; which is a period in time in which the Nazi party used outright political violence to intimidate and suppress competing political parties, especially the communist party. Even prior to this the National Socialist party made efforts to intimidate and consolidate like-minded far right parties, and even conducted an abortive revolt in Bavaria. The appointment of Hitler as chancellor by an aging Hindenburg was naturally the result of loud demands and capitalizing on events that could have been seen as communist agitation. Bearing in mind at all times that Germany and Berlin in specific were the site of a serious communist revolution in 1918. There was as a result an atavistic fear of "Communism" - a veritable red scare. The Nazi's anti-socialist rhetoric and the burning of the Reichstag (being blamed on a communist) was of course all fuel on the fire.
While its true that they saw an upsurge of votes in 1932, they actually lost seats in follow-up elections. Its doubtful if the Nazis could ever have formed government without Hitler being appointed Chancellor and active political intimidation and subversion. The antics of Hitler's party completely undermined the constitution of the Weimar Republic.