Complex sentence: In 2013 and 2014 both houses of the Washington State Legislature (the Washington Senate and the Washington House of Representatives) were under a Democratic majority, though the state senate was under Republican control, due to two Democrats joining Republicans to form a Majority Coalition Caucus.
Split into simpler sentences: In 2013 and 2014 both houses of the Washington State Legislature (the Washington Senate and the Washington House of Representatives) were controlled by a Democratic majority. The state senate was under Republican control, due to two Democrats joining Republicans to form a Majority Coalition Caucus.