A coalition of unions representing state workers have sent Gov. Chris Gregoire a letter saying "enough is enough," they won't renegotiate their health-care agreement.

Gregoire's office, citing a $2 billion budget shortfall, had asked union-represented government workers to reopen the agreement "in order to negotiate a reduction in the employer premium contribution."

The unions responded with a letter Thursday that notes they've already agreed to pay cuts and an increase in their health-care premium costs.

"It is time for other organizations who benefit from the state budget to embrace a fair share of concessions as well," the letter states. Union leaders have called on lawmakers to eliminate tax exemptions that benefit corporations.

The governor negotiated an agreement late last year with the unions that requires state employees to pay 15 percent of their health-insurance premiums, with the state paying the rest. Previously, workers paid 12 percent of the premiums and the state paid 88 percent.

In addition, state worker pay was cut 3 percent through unpaid time off.

Marty Brown, the governor's budget director, said that under state law the governor's office can't force the unions to renegotiate the agreement because it runs through June 2013. Gregoire can only ask them to consider cutting benefits, he said.

The governor's office said it still proposes to reduce by $16 million the state's contribution to employee health-care benefits this biennium. Gregoire's office maintains that would not affect the benefits because workers are tapping their insurance at a lower rate than previously anticipated, so that money would be missed.