Editor’s note: The presidential nominating contests in both parties will come down to the California primary.

For Democrats, 548 delegates are at stake — 11.5% of the total. For Republicans, 172 delegates are at stage — 6.9% of the total. Of those, for Democrats, 158 (29%) are divided proportionally on a statewide basis, while 317 (58%) are divided proportionally by congressional district, with each district providing between 5 and 8 delegates. The remaining 73 (13%) are “superdelegates.”

For Republicans, 13 (8%) are awarded statewide, with ten going to the candidate with the highest number of votes on a winner-take-all basis, and three going to “pre-determined” delegates (the State Chair, National Committeewoman, National Committeeman). Meanwhile, 159 (92%) are awarded by congressional district on a winner-take-all basis, with each district providing 3 delegates.

The result: a district-by-district battle in both parties, which we preview for you here.

CA-45: This landlocked Orange County district is heavily Republican, and is where Ted Cruz chose to launch his campaign in Irvine early April. It includes suburban developments, malls, plazas, mountains and fields, and a large number of long-distance commuters who jam the roadways (the “Orange Crush”). Represented by Mimi Walters, one of the most moderate Republicans in Congress, the district is more competitive than the GOP would like.

Prospects:

Democrats: Though Sanders will attract a few suburban socialists, the district’s Democrats will largely back Clinton.

Clinton 4, Sanders 2

Republicans: Trump will have some support, but this area will remain prime organizing turf for the Cruz campaign.

Cruz 3, Trump 0, Kasich 0

Joel B. Pollak is Senior Editor-at-Large at Breitbart News. His new e-book, Leadership Secrets of the Kings and Prophets: What the Bible’s Struggles Teach Us About Today, is on sale through Amazon Kindle Direct. Follow him on Twitter at @joelpollak.