In a bid to hang on to the remainder of its coveted Race to the Top grant, Hawaii’s teachers’ union will take yet another vote on the new evaluation system that was a centerpiece of the state’s winning application—but now threatens to jeopardize its funding.

The vote comes about a month after a team from the U.S. Department of Education went out to the state to see if Hawaii had been able to make progress in implementing its plan. The state has been on “high-risk” status since December.

The Ed. Dept. team has yet to issue its decision. But clearly folks in the Aloha state are worried that it could result in the termination of its $75 million grant. Hawaii had about $71 million left in its coffers earlier this year, which the state would have to return to the feds if the department determines it’s not following through on its promises.

The Hawaii State Teachers Association is hoping the department will wait until after the vote before it makes any decisions. In fact, Wil Okabe, the president of the union, an affiliate of the National Education Association, wrote a letter to U.S. Secretary of Education Arne Duncan asking him to delay the decision on the fate of the grant until after the revote, according to the Associated Press.

No word yet on whether Duncan will oblige.

This is likely to be a tough vote. The union had already rejected the state’s ambitious plan to base teacher evaluations on student outcomes in a vote earlier this year.

Unlike in other winning states, Hawaii’s teacher evaluation component only exists in its Race to the Top application; it’s not in legislation or regulations. That means the union’s support is critical to its implementation.

The move comes after state officials have tried—and failed—to work around the union. Gov. Neil Abercrombie, a Democrat, said in his state of the state address that Hawaii would make good on its promises—even if it could not persuade the teachers’ union to jump on board.

But a bill that would have made the evaluation system a legal reality without the union’s blessing died in the legislature—dealing yet another blow to the Aloha state’s chances of hanging on to the money.

The state’s Board of Education voted last month to accept a plan that would tie teachers’ pay to their performance. The board is shooting to have the policy in place by the 2013-14 school year. But, without legislation, the plan is still subject to collective bargaining.

A dark horse that surprised everyone when it beat out reform darlings Colorado and Louisiana for a slice of the $4 billion Race to the Top fund, Hawaii is far from the only winning state that has struggled with implementation. But it’s widely viewed as a test case. If the department lets the state keep its grant, it might be a signal to some folks that Duncan isn’t serious about making states hold up their end of the Race to the Top bargain.