The American Federation of State, County and Municipal Employees has donated $100,000 for an advertising campaign against Honolulu City Councilman Charles Djou, a Republican, and former congressman Ed Case, a Democrat, in the special election for Congress.

The national union made the donation in late April to Workers For a Better Hawai'i, an independent labor group that backs state Senate President Colleen Hanabusa, a Democrat, in the special election.

Workers For a Better Hawai'i has spent more than $73,250 on radio ads against Djou and Case so far, according to federal campaign finance reports.

"We think that Djou and Case really haven't supported workers," said Nora Nomura, an officer with Workers For a Better Hawai'i who also serves as deputy executive director of the Hawai'i Government Employees Association, which is under the AFSCME umbrella. The HGEA has also endorsed Hanabusa.

Nomura cited Djou's support for tax cuts for the affluent and Case's backing of President Bush's tax cuts on capital gains and dividends as examples. She said such tax breaks can come at the expense of government spending on public services.

The AFSCME donation is among the largest by Mainland groups trying to influence the winner-take-all vote in urban Honolulu's 1st Congressional District.

Independent Women's Voice, a national conservative group, has spent $237,500 on television ads critical of Case. The Democratic Congressional Campaign Committee spent about $314,000 on television ads aimed at Djou. And the Republican National Committee moved at least $90,400 to the state GOP, which used the money on ads to help Djou.

All three leading candidates have received direct contributions from national donors — Djou, in particular, has benefitted from a national Republican fundraising network — but Mainland groups can also assist through independent spending not directly linked with the campaigns.

Djou is leading in public and private polls, with Case second or tied for second with Hanabusa in most surveys. Many national Demo-crats have said they believe Case has a better chance than Hanabusa of beating Djou, and the fact that Case is a target of both the conservative and labor ads reinforces that impression.

Jason Burke, an adviser to the Case campaign, said Hanabusa and her allies would be attacking only Djou if she thought she could win.

"She knows she can't win so she's attacking Ed. She's more concerned about attacking Ed Case than what's best for the district," Burke said.

"Djou and his band of tea party extremists will spend almost a million dollars attacking Ed because he knows if he was ever in a head-to-head race with Ed he would get beat by 30 points."

Hanabusa's advisers noted that the Case campaign sent out an e-mail yesterday comparing Hanabusa to Ralph Nader, the Green Party candidate who took votes from Vice President Al Gore in the 2000 presidential campaign and "gave us the Bush presidency."

The Hanabusa campaign has also been upset over a Case television ad that implies an endorsement from President Obama based on a quote from an unnamed senior White House official who says he believes Case has the better chance. President Obama, in a telephone message and e-mail to Honolulu voters, has remained neutral between the two Democrats.

"AFSCME, like all independent groups in this election, determines their own message and reaches out in their own way. Clearly, they are concerned about the well-being of the workers they represent, and believe that neither Case nor Djou will act in the best interests of Hawai'i's working families. Colleen will," Eric Hamakawa, Hanabusa's campaign manager, said in a statement.

"As Ed persists in his shameless campaign of misleading commercials and inflammatory e-mails, groups that care about the outcome of this election and the future of Hawai'i will continue to oppose him."

The Djou campaign declined to comment.

Thirty-five percent of the 317,000 eligible voters have mailed back their ballots, according to the state Office of Elections. The deadline to return ballots is May 22; that's when the election results will be announced.