Officials in New York and eight other Northeastern states have come to a preliminary agreement to freeze power plant emissions at their current levels and then reduce them by 10 percent by 2020, according to a confidential draft proposal.

The cooperative action, the first of its kind in the nation, came after the Bush administration decided not to regulate the greenhouse gases that contribute to global warming. Once a final agreement is reached, the legislatures of the nine states will have to enact it, which is considered likely.