Who'll run for Democrats?
No one has thrown their hat into the ring and there isn't anyone who is known to be circling. There are three relatively young Democrats who hold statewide office right now, Attorney General Kamala Harris, LG Gavin Newsom, and Treasurer John Chiang. Each has the advantage that they won't be up for re-election in 2016. So they'll have a free shot at the seat and be able to retain their current post. A lot of people are speculating at a Harris v. Newsom match-up, but John Chiang did better than either in the recent election and polls have shown him with better favorables than they have. Do these candidates want to be in the senate or are they interested in the governor's mansion? They surely won't all get in. Former Los Angeles mayor Antonio Villaraigosa is another possibility.
Los Angeles mayor Eric Garcetti has been mentioned as a possibility, but I doubt he'll run. Garrett has been in office less than two years and isn't that well known. He'd be an underdog agains those giants. The problem that comes in is what happens if he runs and loses. Carmen Trutanich is a cautionary tale. Trutanich pledged to serve two full terms as Los Angeles City Attorney if elected in 2009. In 2012 he decided to run for Los Angeles County District Attorney. His pledge was brought up. He lost the District Attorney race and then in 2013 lost re-election for City Attorney. The Los Angeles mayoral election will be in March 2017. So Garcetti would be asking people to vote for him for U.S. Senate at the same time that he'd have to start running for a second term as mayor. That wouldn't go over well with the public.
In a lot of states the natural transition is from the House of Representatives to the Senate. But no sitting congressman has run for statewide office since 2000 and no Democrat since 1998. The reason is that if a candidate wants to run statewide they have to give up their congressional seat. When you only represent 1/53 of the state you don't have high name recognition and probably don't have the network to raise enough money. I doubt we'll see any of them run.
Who'll run for Republicans? Will it matter?
The GOP didn't run strong candidates for senate in 2012 or for most statewide offices this year. Even those who had some strength, Pete Peterson and Ashley Swearengin, didn't raise a lot of money. So Republicans aren't likely to run a strong candidate in 2016. Even if they do, that candidate will lose. Unless it's former Secretary of State Condoleezza Rice. She has a chance to garner votes outside of the people who usually vote Republican.
Could we see Top Two with two Democrats? Two Republicans?
Possibly on either. It depends on the field. We can probably expect something like 53% Democrats 42% Republicans in the primary. If there are a lot of Democrats but only two Republicans it's conceivable we could see two Republicans finish Top Two. That almost happened in the California Controller's race this year. On the other hand, a bunch of Republican candidates could spread the vote over enough candidates to see two Democrats get in.
We're waiting on Senator Barbara Boxer now.