“We certainly hope that every state feels like it’s in their best interest to create a plan,” Ms. McCabe said. “But we have an obligation under the Clean Air Act, should there be states that don’t submit plans, to be sure we’re ready.”

Republicans and the coal industry were quick to criticize the move.

“Rather than looking to work together to reach common-sense and practical energy guidelines in 2015, the administration is doubling down on its climate crusade at the expense of our economy and our people,” said Mike Duncan, a former chairman of the Republican National Committee and the president of a coal advocacy group, the American Coalition for Clean Coal Electricity.

Ms. McCabe said she expected the E.P.A. to release final versions of the climate change regulations by midsummer, when it would also issue the proposed model rule for states.

Under Mr. Obama, the E.P.A. has proposed two key climate change regulations: one to limit emissions from future power plants, which the E.P.A. unveiled last January, and the other to regulate emissions from existing plants, which the E.P.A. announced in June. Obama administration officials initially said they would release final versions of those rules one year after proposing each one. But on Wednesday Ms. McCabe said that given the complexity of the rules and the difficulty in writing them, it made more sense to release them together.

“It’s become clear to us that there are crosscutting topics on these rules,” she said. “For the overlapping issues, we believe it’s essential to consider these in a coordinated fashion — so we will do them all at once.”