Complex sentence: It is the intention of the party that, if a NOTA gains the majority vote, it should cause an automatic by-election, the idea being that the majority will have given a Vote of No Confidence in the candidates.
Split into simpler sentences: It is the intention of the party that if a NOTA gains the majority vote that it should cause an automatic by-election. The idea being that the majority have given a Vote of No Confidence in the candidates.