Tomorrow's election, with its marquee contest between Daniel Akaka and Ed Case, may be the truest test yet of the changing face of Hawai'i politics.

For years, observers and candidates alike have predicted that Hawai'i's Democratic Party-driven, generally liberal brand of politics is about to change.

They rest their analysis on demographics. More residents, and presumably voters, are not originally from here. They bring Mainland values and ideas and have not been nurtured on the plantation-era, statehood ethos of local Democratic politics.

At some point, they say, the burgeoning districts of West Maui, West Kaua'i and West Hawai'i (and indeed even West O'ahu) will produce an electorate that no longer accepts the union-based, ethnically centered politics of the old days.

But when, exactly, is this supposed to happen?

For some, it already has happened. They point to the election of Republican Linda Lingle four years ago as the moment when the sea change arrived.

And time may indeed tell us that this was the moment.

But Lingle's election to the state's highest office wasn't a pure test of the idea that the political landscape has changed.

For starters, there was no incumbent in the race. Her opponent — Mazie Hirono — had been wounded by a slow start in which she jumped from the governor's race to the Honolulu mayoral contest and then back again into the governor's race.

Meanwhile, Lingle had spent four years single-mindedly building a campaign and momentum.

Second, many nominally Democratic voters were willing to give the "time for a change" idea a test ride. The previous governor, Ben Cayetano, was a contentious sort who had his share of fights with political opponents and even people within his own party.

As his lieutenant governor, Hirono had to carry that baggage.

One can also point to the primary campaign between Hirono and Case, which ended with Case losing by fewer than 2 percentage points. But again, Case's message of "transition" and the importance of moving the Democratic Party to the middle was less well developed than it is this time.

Others thought the test of a changing political tide was when polls suggested Republican President George Bush had a shot at taking Hawai'i away from the Democrats in 2004. The national GOP got all excited, but in the end, John Kerry cashed in on traditional Democratic strongholds and constituencies to win the presidential vote in the state.

All of those side issues are now cleared away.

The Democratic primary is not only likely to settle the race for the U.S. Senate seat. This primary is truly a contest for the soul of the Democratic Party and a test of where the electorate is going.

While much attention is focused on external demographics — the gradual "Mainlandization" of Hawai'i — another factor is also changing our politics here.

That is the changing political focus of the follow-on generations of local-born residents. Young families, two or three generations removed from the plantation era, are building their lives and careers.

Demographically, they look like earlier generations: Japanese, Filipino, Hawaiian and — most predominantly — mixed ethnicities. Their folks likely voted on the Democratic ballot, and they're inclined to do the same.

But their needs are different. They're worried about the cost of living, the challenge of owning a home, where their kids will go to school and traffic, traffic, traffic.

A different brand of politics speaks to them. That's the brand Case is selling.

The key challenge for Case, as it has been for every candidate trying to drive through this seam into the electorate, is that demographics and voter behavior don't match up neatly.

Primary elections, like political conventions and other activities for the faithful, don't closely resemble the larger electorate.

Bluntly stated, voter behavior in a primary is different in the general election. Old-timers tend to vote in larger numbers and in larger percentages than newcomers, and they tend to stick with what they know.

That's true in both the Democratic and Republican primaries. But the action and the numbers have traditionally been on the Democratic side. Here, turnout and loyalty to the cause count — disproportionately.

Let's look at a few comparative districts from four years ago, when Case and Hirono faced off in the Democratic primary:

The Big Island offers a slice of the picture. The 6th state House District (Kailua, Keauhou), while represented by a Democrat — Josh Green — is a classic "newcomer" district with many well-to-do newcomers. It is nearly 50 percent Caucasian (residents, not voters), with the next largest group being folks of mixed race.

In their 2002 primary contest in Kona, Case beat Hirono. But the total number of voters was not much more than a thousand people and the turnout was less than a quarter of all those registered.

Across the island, in the Democratic heartland of the 2nd District, Hilo, Hirono beat Case and the turnout was slightly higher.

But the real impact was on the total number of voters. Around 3,000 folks voted in that primary.

The point here is that more votes went into the Hirono kitty where she was strong than went to Case where he prevailed.

The same picture can be seen on O'ahu. The 23rd District (Waikiki, Ala Moana, Kaka'ako) has long been a Republican stronghold with fair numbers of new arrivals. Residents tend to be older and Caucasian.

Case won that district against Hirono, but the total number of voters was tiny, as was the pathetic 18 percent voter turnout.

Shift to a more traditional Democratic district, such as the 34th (Pearl City, Newtown, Royal Summit) and the picture is much different. There, where Hirono won, the turnout was nearly twice as big as Waikiki, and the raw number of voters was nearly three times that of Waikiki.

So, it's not so much whether a candidate is popular with one group or another. It is whether that candidate can cash that popularity into actual votes.

That, in a nutshell, is the challenge facing Ed Case in tomorrow's climactic primary election.

Reach Jerry Burris at jburris@honoluluadvertiser.com.