The big question is whether state assemblywoman Julia Brownley can consolidate the votes Democrats get. Strickland should get 33-36% of the vote. Parks should get 25-30% of the vote. The Democrats should split 33-38% of the vote. If most goes to Brownley, Parks is sunk. If the other 3 Democrats are able to get at least 10% of the vote, she has a shot.
Parks is going to have to get 65-70% with moderate Republicans and moderate DTS, while getting nearly half of moderate Democrats. This scenario would end up with something like Strickland 32.9%, Parks 28.2%, Brownley 27.7%, other Democrats 11.2%. With 4 Democrats in the race, Parks is unlikely to get much of the liberal vote and the moderate Democratic vote will take some work.
You might say that in a primary that's 37.5% Democratic/37.5% Republican/25% other would mean that Parks won't have to get that many Democrats and Republicans. The problem is that all registrants aren't the same. Leaving the Republican party will hurt Parks with some Republicans and she has little shot with conservatives. They'll make up most of the Republican electorate.
There are some independents that always vote conservative or liberal, even if they aren't a Republican or Democrat. With no 3rd party candidates on the ballot, American Independent voters are very likely to vote Strickland. People who are independents because the Democratic party isn't liberal enough won't vote for her either.
I haven't seen the party vote breakdown in this poll, but it's a Parks internal and that makes it suspect.
Some believe that a Parks-Strickland match-up will heavily favor Parks, as she'll get almost all of the Democratic vote. That might not be the case.
The top two will be more complicated than that. It's common for people to leave the race blank when there's no one from their own party. This includes low involvement/knowledge voters who will get the ballot and be surprised there's no Democrat on it. They don't follow congress or politics, but always vote for Democrats. Then there are the diehard liberals who will know that Parks is really a Republican and think there's no real difference between them. Maybe voting would be smart, but they would never vote for a Republican, even if she says she's not one.
Parks would be able to get most of the moderate Democrats and the liberals who vote strategically. The question is how high this number will be. We'll get a decent idea when looking at the June election in districts like CA-23 where there are only Republicans and an NPP on the ballot. There are 5-6 districts where no Republican will be running.
We can then compare fall off from the senate race in districts with and without both parties.