Supermajorities give the party the ability to raise taxes or override Gov. Jerry Brown's veto without a single Republican vote.
The prospect of one party holding so much power can make it seem as if California's remaining Republican legislators have little hope of having any influence in Sacramento while Democrats pass any law they please.
A longtime Democratic staffer said he does not foresee the party using its numerical advantage to pass every conceivable bill that may be on liberals' wishlists.
"The flood gates aren't going to open to a wave of tax increases and progressive legislation," said Steve Maviglio, who now heads the Sacramento public- affairs firm Forza Communications.
Or, as he put it later:
"It's not going to be legislators gone wild."
That said, Republican Senate leader Bob Huff of Walnut is confident the majority party will go too far.
"Will they overreach? I think you can count on that," Huff said.
Until then, Huff said he still expects Republicans to be able to exert influence in Sacramento and push harder on pension reform.
In September, the governor signed a bill to raise public employees' retirement ages and cap benefits. Huff and other Republicans wanted the law to be changed further to change government workers' pensions from a defined benefit plan to a system in which retirees' benefits would be in part based on market returns, as in a private sector worker's 401(k) plan.
"Obviously, there are fewer Republicans now, but we'll continue to do what I say is the press's job: shine a light on the darkness," he said. "We'll still be calling for reforms of the public pension system. We got part of that way last year."
California Democrats may end up having to show some restraint and willingness to compromise because not every member of their party is the stereotypical Left Coast liberal.
The Democratic Party's more centrist members, especially those whose seats may be most vulnerable to a GOP challenge in 2014 or 2016, may end up playing a role similar that of some Republicans - that of being advocates for business- friendly policies.
"Business is probably going to assume that Republicans are irrelevant and then be looking for moderate Democrats," said Raphael Sonenshein, the executive director for the Edmund G. "Pat" Brown Institute of Public Affairs at Cal State Los Angeles.
It's hard to predict, however, how the Democratic Party will actually play its hand with a supermajority. The Democrats have not held such an advantage since the 19th century, which means nobody has been alive long enough to know what to expect.
"Unlike most things in politics, this isn't something that people have prepared for for years," Sonenshein said. "This has kind of landed like manna from heaven for state Democrats, out of nowhere."
Supermajorities are not unheard of in other states. For example, the Republican Party holds a vetoproof majority in Idaho, a condition that also existed for a time in the 1980s, said the University of Idaho's Marty Peterson.
Peterson, a former budget director for his state, is now the director of a policy research center at University of Idaho. He said policy debates in Idaho tend to take place between the more conservative Republicans and moderate "steelheads," who may find common cause with Boise's Democratic minority.
"They called themselves the `steelheads' because they always swim upstream," Peterson said. "Rather than partisanship making a difference, philosophy makes a difference."
In the 1980s, Idaho's GOP supermajority exercised its power by enacting a right-to-work law limiting the power of unions, Peterson said.
Republican legislators reached the limits of their strength this past year when their conservative wing failed to enact a bill that would have required women to undergo a vaginal ultrasound procedure before receiving an abortion, he said.
Although California Democrats have not held a supermajority in modern politics, they have seen their dominance grow significantly since voters passed Proposition 25 in 2010.
That measure gave the Legislature's Democratic majorities the ability to adopt a budget by a simple majority instead of a two-thirds vote.
Republicans as a result lost their ability to resist Democratic spending proposals as a bloc and force compromises at the end of budget negotiations that during the Arnold Schwarzenegger years, often lasted until late summer.
The GOP minority managed to resist tax increases in 2011, but not so this year. The governor not only succeeded in putting Proposition 30 on the ballot, but also persuaded a majority of voters to approve it, raising their own sales taxes and increasing income taxes on top earners.
The state's nonpartisan Legislative Analyst's Office reported in November the anticipated tax revenues may actually end the state's perennial deficits.
Legislators have a $1.4 billion deficit to solve in 2013. Afterward, California government may actually have enough revenue to enter surplus territory.
Even so, at least two Democratic legislators have put forth additional proposals to raise taxes or fees, although one legislator abandoned that idea shortly after going public.
State Sen. Ted Lieu, D-Redondo Beach, last month floated a proposal to roughly triple the state's vehicle registration fees from 0.65 percent to a vehicle's value to 2 percent of a vehicle's value.
Lieu abandoned the idea five days later, and said his own wife was only half-joking when she said she would lead the opposition to his plan.
More recently, however, San Francisco state Sen. Mark Leno has proposed a constitutional amendment that would make it easier for school districts to raise taxes.
Leno's measure would allow school and community college districts to raise parcel taxes by a 55 percent vote, lower than the current two-thirds majority threshold. Legislative action would not be sufficient to put Leno's proposal on the books - the state's voters would have to agree via the referendum process of lawmakers put the proposal on the ballot.
John Vigna, a spokesman for Assembly Speaker John Perez of Los Angeles, said the state's Democratic Caucus has not yet set an agenda with its supermajority strength in mind.
"The speaker is a very big believer in a collaborative process that involves every member. It's a little too soon to say we're going to focus on Policy X or Policy Y or Policy Z because he wants to make sure that the new members have their input and can bring their experience to the table," Vigna said.
Legislators are set to be sworn in today. Democrats have 29 of the state's 40 Senate seats. That's two more than required for a supermajority. Democrats will also hold 54 of 80 Assembly seats.
Two Senate seats, however, are set to be up for special elections in spring 2013. Sens. Gloria Negrete-McLeod, D-Chino, and Juan Vargas, D-San Diego, won election to Congress and will have to be replaced.
It's also still unknown who will represent the 4th Senate District in Northern California. A Jan. 8 special election is scheduled to decide the outcome between Democrat Michael "Mickey" Harrington and Republican Jim Nielsen.
Staff writer Beau Yarbrough and The Associated Press contributed to this report.
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