There was article 48 which allow the reichkanzler to bypass the parliament. Why did it matter which party was voted for?
The important thing to realize about Article 48 was that it was a form of executive power that was explicitly to be used in emergencies. Article 48 gave the President the power to use military force or bypass both federal and Land (state) governments through decrees. This provision of the Weimar constitution made a certain degree of sense during the constitution's drafting. Not only was the political condition of the country unsettled with left-wing and right-wing inssurectionist parties, it was not entirely clear what impact Versailles would have on Germany. Individual Länder's or the Reichstag's rejection of Treaty repayments could have led to a resumption of hostilities. The framers of the constitution wanted to preserve the maximum degree of latitude for the central government that it could plot the best possible course out of these political rocks and shoals into safer waters.
The problem with Article 48 was two-fold. One, the wording of the constitution provided no mechanism to reign these executive powers in once the emergency had passed.The Reichstag simply had to either accept these decrees as a fait accompli or not, in which case the procedure was to dissolve the Reichstag for new election. This vagueness as well as the expansive powers of Article 48 institutionalized a degree of political conflict within the very fabric of the day-to-day running of government. The second problem was that there was no legal means to determine whether or not the President had invoked Article 48 legally. Unlike the US model, there was no judiciary tradition or mechanism to determine the constitutionality of Article 48 measures. The constitution assumed a silent gentlemen's agreement in which eergency powers would only be invoked in good faith.
This was the major threat of Article 48 for Weimar democracy. It was not so much the broad executive authority itself that was the problem, but that these power needed to be exercised in good faith. Ebert's uses of Article 48 in the 1920s, while flawed on a number of levels, were not done to eliminate the Republic. Ebert still anticipated working with the Reichstag and the political opposition that accepted the Republic's government and democracy. The same could not be said of von Hindenburg's use of Article 48 in the 1930s, which was done at the behest of a conservative camarilla hostile to the very nature of democratic government. Ruling by decree proved to be a habit that was hard to break in this period, but it was Hitler who would use Article 48's powers against the very Republic it was designed to protect. Whether through von Hindenburg or via the strengthened Chancellery after the Enabling Act, Hitler demonstrated the innate flaws of emergency powers whose only brake was a democratic conscience.