Just a few days into the three-week voting period, about 18 percent of voters in the 1st Congressional District have mailed back their special-election ballots to the state Office of Elections.

An estimated 60,000 ballots had been received by the office as of yesterday afternoon, said Rex Quidilla, the office's voter services coordinator.

That's out of 317,337 people eligible to vote in the winner-take-all election for the 1st Congressional District, which stretches from Hawai'i Kai to 'Ewa Beach, Quidilla said.

"It's a sizable amount," he said.

Ballots for the all-mail election were sent to voters last Friday. They must be received by the Office of Elections by 6 p.m. May 22. Results are expected to be announced shortly thereafter.

The race features 14 candidates, among them former Congressman Ed Case, City Councilman Charles Djou and state Senate President Colleen Hanabusa. The winner will serve the remaining six months of the term of former U.S. Rep. Neil Abercrombie, who resigned to run for governor.

The initial surge in returned ballots is consistent with the pattern in two all-mail special elections last year to fill vacant Honolulu City Council seats.

In those elections, there was an influx of ballots returned soon after they were mailed out to voters. That was followed by a lull for a number of weeks, and then a flood of ballots in the waning days of the election.

In the Council District 5 election held last summer that returned Councilwoman Ann Kobayashi to office, about 48,000 ballots were mailed to registered voters on July 17.

By July 28, roughly 25 percent of registered voters had turned in their ballot, well ahead of the Aug. 7 deadline.

The total voter turnout for the District 5 election was 41 percent.

The voter turnout for the District 3 Council election earlier last year was about 45 percent. In that contest, 50.6 percent of total votes cast were received during the first three days of voting, city elections officials said.

Both of those elections, however, dealt with about 90,000 voters each, less than a third of the registered voters in the 1st Congressional District.

The congressional special election will cost slightly more than $900,000. Election officials have estimated that a more traditional type of election would have cost $1.2 million.

Private contractor Hart Intercivic is providing the equipment and technical assistance for the election, including vote counting and mailout.