In 1933, Hitler needed the support of the Center Party to have the act pass, essentially giving the cabinet (i.e. him) full legislative powers.
The center party was divided on the issue, and it took some persuading to get its chairman Kaas to agree.
Assuming the negotiations fail at the last moment (POD: Kaas realizes that the nazis are not going to give him the written constitutional agreements they had negotiated (which were ostensibly being "typed up") and has his party vote against the bill) and the act fails to pass, what kind of consequences might this have ?
Could we potentially see butterflies affecting the Saar referendum, resulting in a narrow vote in favor of the area remaining under French control (maybe as a consequence of many Germans fleeing there from the openly dictatorial nazis?)