A group of 18 states is expected to ask a federal court on Wednesday to intervene in support of Obama administration greenhouse-gas regulations that require significant emissions cuts from hundreds of U.S. power plants. The move will mean most states in the nation are taking sides in a legal battle over a top Environmental Protection Agency initiative on reducing carbon-dioxide emissions. New York Attorney General Eric Schneiderman, who is leading the coalition seeking to let the EPA’s new rules, called the Clean Power Plan, stand, said they are “a critical step forward in responding to the threat of climate change.” Mr. Schneiderman said the intervening states were committed to joining the EPA in defending the regulations aggressively. Mr. Schneiderman said in a written statement that the regulations were “firmly grounded in science and the law” and incorporated strategies that his state and others were using to cut power-plant pollution […]