No. The ‘Rats have a complete hold on the Senate in CA because the rest of the state can’t overcome LA and SF. Look at a map of the current Congressional delegation. Presuming the state-wide races in the new states followed the bulk of the congressional races in the same areas, Jefferson, Central CA, and South CA would most likely elect GOP senators, Silicon Valley and Western CA would elect ‘Rats, and Northern CA would probably lean to the ‘Rats but would be competitive.
The plan would actually improve the partisan composition of the Senate.
Comparing the county maps from the 2004 Presidential election give the same picture, though Obama did better in 2008 and 2012 and would have lost Jefferson, and maybe Central CA, and carried the other four. Still, with a little work, for the future, it would also shift the electoral college to the right.
Most of the counties in NorCal above Sacramento are strongly conservative. Mendocino and Humboldt counties are pretty lib, but can be overcome. Depending on the demarcations, the Senate division could be a 6-6 split, vs. the guaranteed lock for the dems. Also, it breaks apart that 55-EV guarantee the dems get every President election as well. Splitting that mess up out there would be a great idea.
But splitting the Bay Area into two states just spreads the madness. That makes North California, Silicon Valley, and West California solidly blue. South California has a strong illegal immigrant contingent and would no doubt “pioneer” amnesty. Jefferson might be OK, but you have the granola-crunchers in Redding and Crescent City to worry about.
I can’t imagine CA being much better off going this way, but I could be wrong.