Nearly 200 voters have cast absentee ballots for the Sept. 23 primary election, and thousands of others will begin receiving their ballots early next week.

And with just hours left before today's voter registration deadline, the number of registered voters has increased by approximately 24,000 over the 2004 primary. More than 650,000 voters are registered so far, up from 626,000.

Less than four out of 10 registered voters actually cast ballots in the 2004 primary — but more than three out of 10 who did vote cast an absentee ballot before election day. A similar chunk of the electorate is expected to vote absentee this election. Approximately 175 Kaua'i voters have already done so by mail, officials there said.

Any voter may request an absentee mail-in ballot without citing a specific reason or need, and the convenience of voting by mail has made it a growing trend in Hawai'i and on the Mainland.

Well-financed and organized campaigns also target absentee voters aggressively to get votes "in the bank" for their candidates before election day. Campaigns can identify likely supporters and help them request absentee ballots, then follow up to make sure they cast their votes.

More than 53,000 voters have requested absentee mail-in ballots so far, about 45,000 of them on O'ahu.

Neighbor Island counties had far fewer applications to process, and were the first to get ballots out to voters.

Kaua'i began sending out ballots on Aug. 17, while Maui and the Big Island began sending them out this week, according to officials from each county. O'ahu voters who requested absentee ballots should begin receiving them early next week, according to Honolulu elections administrator Glen Takahashi.

Additional ballots will be sent out in each county as the applications are received and processed. The majority of absentee voters tend to cast ballots closer to election day, after the pace of campaigning has picked up and candidates have become more visible.

More than 280 candidates are running for 120 federal, state and county offices in the primary election. For most offices, the top vote-getters from each political party will face off against each other in the general election.

Eligible voters can request mail-in absentee ballots for the primary until Sept. 16. Voters can also cast absentee ballots in person from Sept. 11 to Sept. 21 at designated polling places, and don't need to request applications in advance.