The Hawaii State Teachers Association has rehired Wilbert Holck to replace Al Nagasako as its executive director, the union announced Wednesday.

Holck is rejoining the HSTA from the Hawaii Government Employees Association, where he had been deputy executive director of field services for the state’s largest union. The former Kaiser High School teacher previously worked for the teachers union for more than 20 years, serving as the HSTA’s deputy executive director and as a UniServ (Unified Staff Service Program) director.

"I am honored to be back at the HSTA, where I called home for nearly 25 years," Holck said in a statement. "Starting out as a teacher, it is nice to come full circle and be able to serve fellow members and advocate for quality education in Hawaii."

Holck started his new job Wednesday, but the union, which represents some 12,500 public school teachers, said Nagasako will stay on through Jan. 5 to help with the transition.

Some union insiders have said privately that Nagasako stepped down because of a possible campaign spending violation connected to the union’s fight against a proposed constitutional amendment that voters ultimately rejected.

The union — which opposed the move to allow public funds to be spend on private preschool programs — initially began funding an advertising campaign against the amendment through its political action committee, or PAC, which is funded by member dues. PACs, in general, make or receive contributions and make expenditures to influence the election of political candidates.

That posed a problem because PACs are subject to state campaign contribution limits, meaning the HSTA wouldn’t have been able to accept a $275,000 contribution from the National Education Association to fight the preschool amendment.

The union subsequently pulled a TV ad it paid for using PAC money, while a group of retired HSTA officers formed a so-called ballot issue committee, which can take in unlimited contributions exclusively to lobby for or against any question or issue appearing on the ballot.

That committee, For the Future of Our Keiki, reported a single contribution: the $275,000 from the National Education Association, its national affiliate, according to campaign-finance reports. It spent a little more than $134,300 between Aug. 10 and Oct. 20, mostly on TV and radio ads against the amendment.

The amendment failed to get the needed votes to pass.

Gary Kam, general counsel for the state Campaign Spending Commission, said there are no pending violations against the union or its PAC.

HSTA President Wil Okabe said Nagasako is leaving the union because he is retiring, and called the allegations about Nagasako resigning over the campaign spending mixup speculation.

"Al and I met several months ago and he told me that he wanted to retire," Okabe said. "I can understand the speculation because there was a situation with the constitutional amendment, but that wasn’t the factor."

HSTA paid Nagasako a base salary of $138,618, according to the union’s most recent tax filing with the IRS, and $18,900 in "other compensation."

The change in leadership comes at a critical time for the union. Teachers’ 2013-17 labor contract includes a so-called "reopener clause" allowing HSTA to negotiate for increased compensation once a salary study called for in the contract is completed. The study is scheduled to be presented in the upcoming legislative session.