The Abercrombie administration agreed to a “favored nation” clause in a tentative contract with the Hawaii Government Employees Association that gives the union the ability to match gains won by other unions, sources say.

The “favored nation” clause is essentially a reward for the HGEA, the state’s largest public-sector labor union, for being the first of three public-sector unions now negotiating with the Aber­crom­bie administration to reach an agreement, sources said. The administration is also in contract talks with the Hawaii State Teachers Association and the United Public Workers.

The “favored nation” clause, sources said, helps ensure that the contract talks progress toward uniform concessions with labor.

Gov. Neil Abercrombie and the HGEA announced Wednesday a tentative contract that includes a 5 percent pay cut for public workers and an even split between state and county governments and public workers on health care premium costs. Public workers will also receive an additional six hours of paid time off each month, or nine days a year.

The Abercrombie administration and the HGEA have declined to publicly provide any additional details. The union is expected to inform workers today about specific provisions in the potential deal.

The HGEA’s more than 28,000 state and county workers must vote to ratify the tentative contract.

Abercrombie said Wednesday that he had support from Big Island and Kauai mayors but was still discussing the details with the Hono­lulu and Maui mayors. Under state labor law, Aber­crom­bie must get at least one of the county mayors to sign off on the agreement.

Honolulu Mayor Peter Carlisle was critical of the tentative contract. He said the additional paid time off for public workers would make it closer to a 3.5 percent pay cut than a 5 percent reduction. He equated the extra time off to vacation days.

“People are not working and yet they’re getting paid, so to my mind that’s a vacation day,” Carlisle said last night on “Insights” on PBS Hawaii.

Other sources familiar with the contract said the additional paid time off helps offset the pay cut and higher medical costs while also ending the furloughs that are part of the existing contract.

One source described it as a “flexible furlough” because government offices and operations would not shut down when workers take the extra time off.

State House Republicans criticized the potential deal as “expensive and unfair” because it does not

preserve the equivalent of two furlough days a month in the existing contract.

Abercrombie has said he would seek 5 percent labor savings from unions — the equivalent of one furlough day a month, or $88 million a year. The governor said the HGEA contract would save about $65 million in fiscal year 2012 and about

$59 million in fiscal year 2013. Similar deals with the HSTA and UPW would likely put the governor close to his target. But Republicans and several Dem­o­crats have said that additional labor savings are needed to help with the state’s projected $1.3 billion deficit over the next two years.

“This is a deceptive sleight of hand to claim this deal saves money,” state Rep. Cynthia Thielen (R, Kai­lua-Kane­ohe), said in a statement. “Taxpayers are being misled when in fact they will be paying for government workers to stay home.”