PORTLAND – The outlook for Maine’s general obligation rating has been lowered from stable to negative by one of the three major bond-rating agencies that track the state.

Standard & Poor had told Maine that its credit rate is being threatened by the sluggish economy.

The general obligation rating is an indication to potential investors of the state’s likelihood to repay bonds. General obligation bonds are those that are backed by the state and paid off with general fund tax dollars.

The outlook is different from the state’s rating.

The state is now rated at AA-plus, Standard & Poor’s second-highest rating. Lowering the outlook is not a ratings change, but a warning that one may follow if the economy doesn’t improve, said Geoffrey Buswick, associate director of public finance ratings for S&P’s Boston office.

“The outlook does not really tell the future,” Buswick said. “If it’s a case where fiscal year ’03 continues to have trouble hitting targeted revenue numbers and the state didn’t take any action,” the rating could be downgraded.

The credit rating is a factor in how much interest the state is charged when it issues bonds. A higher interest rate increases the burden on taxpayers.

Ten states have received negative outlooks, Buswick said.

Marc Cyr, principal analyst in the state Office of Fiscal and Program Revenue, said the outlook should not be taken as a sign that Maine’s credit is in danger.

“They’re saying, ‘If something’s not done, you’re going to have a problem,”‘ he said. “But in Maine, action has to be taken because we have to have a balanced budget.”

Even if Maine’s credit rating is downgraded and interest goes up, the state’s bonds could still be a good investment, especially if interest rates remain very low, he said.