Tuesday's Primary Races Were Key For Both US Parties

Tuesday night marked another big night of primary elections. Eight states held primary elections either for governor, House or Senate races. Here's a quick rundown of the most-watched races: 

For Democrats, California could be a make-or-break state. The party is challenging seven GOP seats in districts Hillary Clinton won in 2016. 

But there's a catch: The state has nonpartisan, open primaries. That means the top two vote-earners advance to the midterm election. Democratic leaders are afraid some districts could end up with two Republican primary winners, since the race is jam-packed with Democratic challengers who may split the vote and keep each other out of the top two spots.

New Jersey, on the other hand, could be a big win for Republicans — the party hasn't had a senator there in decades. 

Democratic incumbent Robert Menendez has been mired by a scandal. Bob Hugin won the GOP primary and will challenge Menendez in November.

Democrats are also taking big steps in two other states. 

Inspired by Doug Jones' surprise victory to fill Attorney General Jeff Sessions' Senate seat, the party is challenging every House GOP seat in Alabama. Three Democrats ran unopposed in Tuesday's primaries: Peter Joffrion, Danner Kline and incumbent Terri Sewell. 

The party is also considered competitive in one of the three Republican-held Iowa districts.