Complex sentence: Many states accomplish the same requirement by having simultaneous registration dates for the primary and the general election; in fact only the states of Connecticut, Iowa, New York and Vermont have neither a sore-loser law nor simultaneous registration deadlines.
Split into simpler sentences: Many states accomplish the same requirement by having simultaneous registration dates for the primary and the general election. Only the states of Connecticut, Iowa, New York, and Vermont have neither a sore-loser law nor simultaneous registration deadlines.