The state of Nevada was one of the few bright spots for Democrats last year: not only did Hillary Clinton carry the sate 48-46%, but Democrat Catherine Cortez Masto (by a 47-45% margin) kept the seat of former Senate Majority Leader Harry Reid in Democratic hands. Furthermore, Democrats picked up two U.S. House seats (winning three out of four seats) and retook control of the state legislature.
Nevada will also see a U.S. Senate race next year, and this time, first term Republican incumbent Dean Heller is up for re-election. In addition to the Democratic victories last year in his home state creating some re-election challenges, he was only elected to a full term in 2012 (he was appointed to the seat in 2011) by a narrow 46-45% margin. However, Senator Heller has more immediate problems: he has a substantial primary opponent (Danny Tarkanian, who is the son of former UNLV basketball coach Jerry Tarkanian), and Nevada is a “closed primary” state, meaning that only registered Republicans (and registered Democrats, for that matter) can vote in their respective party primaries.
JMC recently polled this primary race in August, and was recently out in the field again (poll can be found here). Given that Democrats only need a net gain of three seats to retake the U.S. Senate, there are several races which will determine control of the U.S. Senate. Arizona is one of those states, particularly since Sen. Jeff Flake recently decided against seeking re-election (JMC polled that race in August as well, two months before his decision not to seek re-election). Nevada will be another.