As a sign of things to come, they point to last week's special election win by Bill Foster, an unknown Democrat, in recently retired GOP House Speaker Dennis Hastert's congressional district.
"Republicans are trembling all over America, including in the California state Legislature, that a Democratic tsunami is coming," state Democratic Party campaign adviser Bob Mulholland said.
If a wave does crash down on California, Democrats hope it sweeps through at least six Assembly and two Senate districts, which is what they'd need to capture a two-thirds majority in both houses. That would give them the power to pass budgets and taxes without Republican help.
Republicans admit to being nervous about the national mood, but say several factors could work against California Democrats. For one, both parties have been insulated with safely drawn districts since the last time legislative boundaries were drawn, in 2001.
Democratic leaders, needing a two-thirds vote to avoid a court challenge to their newly drawn lines in 2001, brokered a deal with Republicans to protect incumbents, leaving virtually all seats unassailable.
"If they had drawn more competitive seats," said Jack Pitney, a political science professor at Claremont McKenna College, "a real tidal wave might wipe out Republicans.
Also, with California considered a solidly blue state, said GOP consultant Matt Rexroad, it's unlikely
Neither presidential nominee would spend much time in California or money in television advertising.
"What will motivate Democrats to turn out?" Rexroad said. "How much excitement will be generated in TV ads?"
But in the age of the 24-hour news cycle, YouTube and MySpace, Democrats say, Californians won't have a problem getting caught up in a national fervor for change.
And, as demographics shift, more Democrats are moving into some Republican seats and old district boundaries are becoming moot, said Bill Carrick, a Democratic consultant and veteran of presidential campaigns.
"I think there will be seats in play that people will be surprised about," Carrick said. "A big partisan surge usually works everywhere and you see pickups in places you didn't think would happen.
"We're at the end of an unpopular presidency, with the economy going to hell, and an unpopular war," Carrick said. "The dynamics are here for a big change. There are big things going on."
In every Democratic primary and caucus so far, record numbers of Democrats have turned out and have dwarfed GOP turnout.
Tony Quinn, a former Republican legislative aide who specialized in redistricting, said he doubts California Democrats can exploit the national mood.
"I don't see the Democrats having the candidates in place to take advantage of the tremendous wave they claim is there," said Quinn, co-editor of the California Target Book, which analyzes legislative races. "I don't deny the potential for a big wave, but I don't see that they've laid the groundwork for it."
For one, they failed to field a Democratic candidate in one of the Legislature's rare competitive seats, the 15th Senate District, held by Sen. Abel Maldonado, R-San Luis Obispo. Despite holding a four-point registration advantage, Democrats decided he was too strong an incumbent to challenge.
Still, Democrats have set their sights on GOP seats in five Assembly districts and two Senate seats, all but one of which is now open due to term limits -- and all having moved significantly to the left in party registration.
For example, in the 15th Assembly district, currently held by term-limited Guy Houston, R-San Ramon, the Republicans' registration advantage has shrunk in six years from 14,000 to 272. The district covers parts of Alameda, Contra Costa, Sacramento and San Joaquin counties.
In the 78th, in San Diego County, under Republican control since 2002, Democrats outnumber Republicans by 17,188, an increase of 4,000 since 2006.
In the 80th, in Imperial and Riverside counties, and also held by a Republican since 2002, Democrats hold a 15,480 registration advantage over Republicans, a jump of 5,000 since 2002.
Democrats also are keeping an eye on the 26th, held by outgoing Greg Aghazarian, R-Stockton, and the 10th, held by term-limited Alan Nakanishi, R-Lodi. Registration is even in the former, while the GOP advantage is only 3 percentage points in the latter.
Even if they took all five Assembly seats -- and held onto all of their own -- Democrats would have to overcome huge odds to win a sixth seat. In only one other open seat, the 36th Assembly district in San Bernardino County, are Democrats within 6 percentage points in registration.
In the Senate, Democrats have targeted the 19th district, now held by term-limited Sen. Tom McClintock, R-Thousand Oaks, where Republicans have a 3-point registration edge.
Democrats are also in the midst of a recall campaign against Sen. Jeff Denham, R-Merced, in a district that has a 10-point Democratic registration advantage. That battle could wind up on the June 3 ballot, and could foretell what kind of political atmospherics are in store for the fall.
In some Republican seats, President Bush is polling as low as 12 percent, said Paul Hefner, a campaign spokesman for Senate President Pro Tem Don Perata, D-Oakland.
"With these numbers," Hefner said, "there are no safe Republican seats. In this kind of atmosphere, our prospects are looking pretty good."
Reach Steven Harmon at 916-441-2101 or firstname.lastname@example.org.