HAMPTON, N.H. (AP) - A program that reduces power plant emissions in the Northeast is being eyed by states looking to take action to reduce greenhouse gas emissions.

The Regional Greenhouse Gas Initiative includes nine Northeast and Mid-Atlantic states. It has been credited with reducing carbon dioxide emissions by 30 percent since 2008 in those states.

It also has returned $2.8 billion to those states from the auctioning of permits allowing power plants to emit carbon dioxide. That money mostly goes to renewable energy and energy efficiency projects, which helps the environment and brings down utility bills.

Virginia announced it is taking steps to become the first Southern state to join the regional cap-and-trade program, while New Jersey has promised to rejoin the pact.

If they get on board, member states would represent a combined gross domestic product of $3.9 trillion, equivalent to the world's fourth-largest economy.