PORTLAND — The credit rating agency Moody’s Investors Service has upgraded its outlook on Maine bonds to stable just before the expected sale of $115 million in state debt.

Moody’s said in a statement Wednesday it expects the general obligation bonds will be sold June 12, and the sale amount may change. The credit rating on those bonds, which is a third-highest ranking of Aa2, did not change but is below average for U.S. states, according to Moody’s.

The service said it changed the outlook on Maine’s general obligation bonds because of a “stable revenue picture, progress towards structural balance and actions to address liabilities related to pensions and retiree health costs.”

Republican Gov. Paul LePage said the change is an affirmation of his policies. “If there is one lesson to take away from the Moody’s rating, it is that Republican reforms are working for Maine,” he wrote in a statement released Thursday morning. “It was Republican efforts to repay our hospitals, reform the public pension system, and maintain the balance of the budget stabilization fund that led Moody’s to improve their outlook for our state.”

Still, Moody’s noted, the state’s economic recovery lags the rest of the nation and demographic trends do not stand in the Maine economy’s favor.

The rating service had first downgraded its outlook on Maine’s general obligation bonds in May 2012 and affirmed that outlook in last year.

The service said the state could improve its rating by maintaining positive available fund balances, showing job growth in high-wage occupations and establishing structural balance in the state budget. The rating could drop if the state has more budget gaps that require one-time fixes, more borrowing for regular operations and worsening economic trends.

The state’s bond rating had become a political issue during the last legislative session as lawmakers borrowed from the state’s rainy day fund to lower cuts to its revenue sharing with cities and towns. Gov. Paul LePage said the move would hurt the state’s credit rating and lobbied for a law that replenished rainy day funds using about $21 million in excess funds from state employees health insurance accounts and unspent money in the Department of Education.