In this task, you are given a question and a context passage. You have to answer the question based on the given passage.
Q: What could have been a threat to the signatures being obtained?, Context: Despite the disagreements on the Eucharist, the Marburg Colloquy paved the way for the signing in 1530 of the Augsburg Confession, and for the formation of the Schmalkaldic League the following year by leading Protestant nobles such as John of Saxony, Philip of Hesse, and George, Margrave of Brandenburg-Ansbach. The Swiss cities, however, did not sign these agreements.
A: 
disagreements on the Eucharist