The Nazis started their power grab in earnest after the arsoning of the Reichstag. Even before that incident, public opinion was actually already firmly against the communists. To this day there are debates on who exactly arsoned the Reichstag, but it was suspiciously convenient for the Nazis so they could blame the communists. Soon after this incident, laws were passed that effectively abolished the constitution and granted the Nazi the power they required to establish their rule.