From Chris Cillizza this morning:

A look at the Real Clear Politics polling average in the race, however, suggests that California is a genuine tossup as Boxer holds a narrow one-point edge.
Republicans, buoyed by their new numbers, insist that despite the state’s clear Democratic lean — the last Republican to win a Senate race in the Golden State was Pete Wilson back in 1988 — they are in the game thanks to Boxer’s lingering unpopularity and a national breeze blowing in their direction.
One Democratic strategist who has worked in California politics expressed a level of pessimism about the race. “I gotta think that even in CA, a liberal career politician is a tough place to be in a change year,” said the source who was granted anonymity to give a candid assessment of the race.
Publicly, Democrats express considerable confidence, noting that while the race has tightened somewhat — thanks to considerable spending by Fiorina — Boxer enters the final days of the campaign with a three-to-one cash-on-hand edge. Barring Fiorina writing a huge check, they argue, it will be impossible to match Boxer’s spending over the final 12 days.