Voters are casting ballots early and in record numbers.

More than 10 percent of all registered voters had already cast their ballots by Saturday, with another week of absentee voting in the primary election still to go.

Most of the activity is via mail-in voting.

Rex Quidilla, state Office of Elections voter services coordinator, said some 75,000 voters requested mail-in ballots, and county elections officers told The Advertiser that some 50,000 had been received in their offices by Saturday.

Additionally, about 16,000 people had cast ballots at the 13 walk-in voting sites that opened Sept. 11 around the state. Counting walk-in balloting, more than 66,000 ballots had been cast by the end of the day on Saturday, out of 655,741 registered voters.

"Certainly on the mail side, it's higher than we've seen before. We still have some mail from the weekend to process," said Glen Takahashi, election administrator for the City and County of Honolulu.

Kaua'i County elections officer Lyndon Yoshioka said his county's experience is similar.

"The mail has probably doubled. Several candidates have really pushed it," Yoshioka said.

The rise in early voting is a function of increased sophistication on the part of political parties and individual campaigns, said political scientist Neal Milner, who was recently named University of Hawai'i ombudsman.

"Over the years, political organizations have developed a way to identify the likely voters, and they are able to encourage them to vote earlier," he said.

Milner said a high early turnout may not predict a high turnout overall. Indeed, Milner said this is a low-turnout year nationwide.

"I think this election (in Hawai'i) is going to have a low turnout. A really competitive race in Wisconsin just had a turnout in the 20s (percent)," he said.

With overall voting numbers dropping, the impact of the early vote gains importance. UH political scientist Ira Rohter said campaigns urge their supporters to vote early both to ensure the vote is cast and to prevent any last-minute change of mind.

"It insulates them from something that happens at the end of the campaign. You're afraid that something may happen and people could change their minds," Rohter said.

The focus on early votes has changed the tempo of campaigns, which once built to an election-eve crescendo.

"In a way, it has made campaigns more complicated. It's all about mobilizing your voters. It gives a big advantage to early organizing," Rohter said.

Both Milner and Rohter said the campaigns — particularly the Democratic primary U.S. Senate battle between Rep. Ed Case and Sen. Daniel Akaka — are certainly big factors in the size of the mail-in voting turnout. But both also said that the convenience of early voting and mail-in voting is a convenience that can't be ignored.

Absentee voting has represented an increasing part of the vote ever since voters no longer were required to cite reasons why they could not vote on election day. The absentee vote tends to be smaller in primaries than generals, and it reached a historical peak of 21 percent of all registered voters in the Hawai'i general election of 2004.

"This has been a historical trend. I think people are busier now than they ever have been," Rohter said.

The walk-in and mailed ballots will not be counted until the primary election on Saturday.

Absentee walk-in balloting will continue through Thursday afternoon. The polls will be closed Friday, and will reopen at 7 a.m. Saturday across the state and remain open until 6 p.m. Mail-in ballots will continue to be accepted through an afternoon mail pickup on Saturday.

Elections officers are still short of volunteers to help staff the polling places.

Those interested in volunteering to help on election day can call 211 and leave their information, or input their names at the state elections Web site at www .hawaii.gov/elections/volunteers.

Reach Jan TenBruggencate at jant@honoluluadvertiser.com.