In 2018 Democrats took control of the New Hampshire General Court (the state legislature) in a big shift. Previously the Republicans had controlled the Court with a 14-10 majority in the Senate and a 216-176 majority in the House. But then in November 2018 Democrats won control by winning a 14-10 majority in the Senate and a 233-167. So, it was a big change.
What are the reasons put forward to explain this big change in balance of power?