In recent years, some pollsters, pundits and consultants have pointed to declines in partisan voter registration, along with Gov. Arnold Schwarzenegger’s two elections, to question California’s reputation as a left-leaning “blue state” and to argue that it is in fact a post-partisan “purple state.”

Exhibit A, for the post-partisan advocates, is the voter roll: Democratic registration stands at 45%, down 12% since 1978; Republican registration is 31%, down 3%, and independents now represent 20% of the voters, up 12%. These data, it is argued, prove that partisanship is waning and California is evolving into a bastion of independence.

Here at the Calbuzz Repository of Analysis and Policy, we’ve never bought the neo-kumbaya thesis. It’s long been our view that while political parties, like other large institutions –- corporations, unions, metro newspapers, etc. –- have become atomized and decentralized in the modern era, political behavior is pretty much like it’s always been.

And the Field Poll’s release of a new study of 30 years of voting patterns last week offers further evidence that advocates for the post-partisan theory  misread our history and attitudes. While Field’s data confirm the long-term trend of voters increasingly bypassing both parties to register as independent declines-to-state, their analysis also shows that these independents reliably think and vote like Democrats most of the time.

Consider, for example, voter attitudes on same-sex marriage – one of the most incendiary issues in California politics. Back in 1977, Democrats were opposed 29-63%, Republicans were opposed 30-65% and independents and others were opposed 38-55%. Three decades later – in 2009 – Republicans have hardened their opposition to 23-68%. But Democrats have flipped their position to 64-30% in favor and so have independents — to 57-38% in favor.

Likewise on abortion rights, another divisive issue. Back in 1975, a narrow majority of California voters approved of abortion rights, with Republicans in favor 50-44%, Democrats at 52-43% and independents at 59-34%. By 2006, 70% of voters overall favored abortion rights and the big movement came among Democrats, now 82-10% on the issue and independents at 73-14%. Republicans’ attitude on the issue moved only slightly, to 55-40% in favor.

As Mark DiCamillo and Merv Field explained in the Field Poll release, public attitudes about death and taxes haven’t moved much, but on social issues like same-sex marriage, abortion and euthanasia,  “California voters, especially Democrats, have become more socially tolerant” over the past three decades. What’s important in the numbers is that independents – while there are more of them – function for all intents and purposes as if they were unregistered Democrats.

The purple state thesis was stated perhaps most forcefully –- and mistakenly — by GOP consultant and former Schwarzenegger communications director Adam Mendelsohn during last year’s presidential elections, when he predicted in September that John McCain was “exactly the kind of Republican” who would be competitive amid the purple hues of the Golden State.

“Certain Republicans are able to win in California and when you have a Republican , like John McCain who has a proven track record of reaching out to independents, reaching out to disaffected Democrats, this is something he built a career on doing. It’s exactly the kind of Republican who poses a real opportunity for us in California,” Mendelsohn told Fox News in September, adding that “California (is) not a red state, or a blue state, but a purple state.”

Others, like Dave Lesher and Mark Baldassare of the Public Policy Institute of California have made the case more subtly, arguing that because California’s independents combine strains of social liberals and fiscal conservatives, “their vote is up for grabs.”

“Independents’ attitudes, in contrast to that of Democrats and Republicans, don’t fit neatly into traditional liberal and conservative camps,” the two wrote in a LAT op-ed in 2006, adding that this made for “a surprising degree of uncertainty and volatility.”

In fact, it hasn’t. The analysis of fiscal conservatism is based on a single issue: the long-standing strong support of Proposition 13 by voters of every ideological stripe. But by almost any other measure, the notion that independents have their finger to the wind in every election cycle is, we think, not right.

For starters, the rise of independent registration has not been accompanied by the surfacing of any independent political movement. Setting aside the Superintendent of Public Instruction (a nominally non-partisan office) no one has been elected to a statewide office without partisan identification. Beyond that, independents have sided with Democrats most of the time.

– Democrats have won the state in five of the eight presidential elections since 1978 and have made a clean sweep since 1992, when the move towards independent voters started gaining steam. (And no candidate who opposes abortion rights, on which independents have moved left, has won at the top of the ticket, i.e. for president, governor or senator, since George H.W. Bush beat Michael Dukakis here in 1988.)

– Democrats have dominated every single Legislative session except for the anamolus “Contract with America” election of 1994, when Republicans briefly held a majority.

– Democrats have controlled most of the statewide constitutional offices in the last 30 years, buoyed by independent backing.

The purple staters’ best case is the history of the governor’s office which, since Jerry Brown’s re-election in 1978, has been won only twice by a Democrat, who was tossed out before finishing his second term.

But even in the case of the governor, California independents –- with their Democratic-leaning tendencies on social issues and their centrist outlook on fiscal issues –- have for two decades only rewarded the GOP when they have fielded relative moderates like Pete Wilson and Arnold Schwarzenegger.  When the GOP has tried to win statewide with one of their red-meat candidates (see: Dan Lungren, 38%, and Bill Simon, 43%) they have been crushed by their inability to win independents.

It is undeniably true that voters are increasingly declining to declare themselves either Democrat or Republican when they register to vote. But scratch an independent in California and you find a voter who leans Democratic.

If the Republicans were to nominate a fiscally moderate, pro-choice, pro-environment candidate who is not seen as virulently anti-immigrant or anti-gay, that candidate might well attract enough independents (and Democrats) to win at the top of the ticket. But it’s unclear that such a candidate can win a Republican primary without first lurching so far to the right as to be poisoned in a general election (recall that Schwarzenegger never had to run in a contested primary, and that Wilson first won nomination after being drafted from the U.S. Senate by GOP leaders as the party’s best hope of ensuring a competitive reapportionment).

The problem with confusing independent voter registration with independent voting behavior is that it leads to the kind of thinking Schwarzenegger’s former communications director engaged in when he told the SF Chronicle in 2008:  “John McCain will give a Hillary Clinton or Barack Obama a serious run in any purple state like California.”

Calbuzz sez: Purple staters can argue that ’til they’re blue in the face, but they’ll still end up red-faced with embarrassment.