Voter turnout for today's election will likely set a record low for a presidential primary in California, with just 35 percent of registered voters casting ballots, according to the Field Poll.

The estimate reflects the state's insignificance to the Republican presidential nominating contest, which was settled long ago, and to a dearth of competitive, high-interest races statewide.

"There's really no comparison," poll director Mark DiCamillo said. "We've never had a turnout at this level before for a presidential primary in California."

In a report released today, Field estimates 6 million people will vote in the election, 35 percent of registered voters and just more than 25 percent of all Californians who are eligible to vote.

In the 2008 presidential primary, turnout reached almost 58 percent.

If turnout today falls below 40 percent of registration, as Field expects, it will be for the first time in the modern era. The previous record low turnout for a presidential primary was 41.9 percent in 1996.

That election was similar in significant ways to today's: As with President Barack Obama and Republican Mitt Romney this year, the Democratic presidential candidate in 1996 was the incumbent, Bill Clinton, and the Republican, Bob Dole, had the nomination safely in hand.

For voters uninterested in the presidential primary election, there is little down ticket to seduce them.

Neither Proposition 28, involving changes to the state's term-limits law, nor Proposition 29, a proposed tax on cigarettes, is likely to drive up turnout significantly, DiCamillo said, and in the U.S. Senate race, Dianne Feinstein faces no serious opposition in her re-election bid.

"You're going to have the regular people show up, the people who vote no matter what," poll director Mark DiCamillo said, but "by and large statewide, it's going to be very, very low."

Just more than 6.1 million voters participated in the 1996 election. The last year fewer than 6 million Californians voted in a presidential primary was 44 years ago, in 1968.

Turnout that year was a near record-high 72 percent.

Among the many registered voters who do not plan to vote today is Joe Holt, an actor from Los Angeles.

The 42-year-old independent voter said he's "not a huge fan of the initiative system."

He said he probably would cast a ballot if the presidential election was contested.

Since it's not, Holt said, "I guess I don't feel all that tied to the results until the general election comes along."

In 2008, when turnout was nearly 58 percent, the primary election was held in February and the presidential contest was still competitive when it reached the Golden State. DiCamillo attributed decreased voting in today's election to legislation last year moving the contest back to June.

The lower turnout is likely to result in a higher proportion of older people voting than in other elections, DiCamillo said. Field estimates 60 percent of voters today will be age 50 or older. People of that age group account for just 45 percent of all registered voters.

While estimating overall turnout to be abysmal, Field predicted a significant rise in the proportion of ballots that are cast absentee. The proportion of absentee voters has been growing steadily for years, and for the first time in a California presidential primary election, the poll estimates, a majority of voters – 55 percent – will vote by mail.

"Once you decide to vote by mail, you're very likely to do it again and again," DiCamillo said. "Most people think it's a more thoughtful vote. Plus, they have a lot more time to do it."

Cynthia Folsom, of Clovis, is among those voters who have already submitted their ballots. She said she votes regularly in part because her husband "feels very strongly about politics and about taking care of our country."

Folsom thinks voting is important, too, but she said it can be depressing.

The 43-year-old Republican said voters may be affected by the weak economy and pessimism about the state – that a "kind of dark outlook on life is maybe bleeding over" into the polls.

Depressed or not, voters surveyed appeared to be comfortable confronting California's new top-two primary system, in which candidates in races other than for president appear on the same ballot regardless of party affiliation, with the top two vote-getters advancing to a November runoff.

The poll found 74 percent of voters do not think the change will confuse them, while 21 percent said it will.

Of those who said they expect the format to be confusing, just 5 percent believe they will be very confused.