The Environmental Protection Agency has confirmed plans to delay the first-ever limits on greenhouse gas emissions from new power plants. The rules would have forced new power plants to keep emissions under 1,000 pounds of carbon dioxide for every megawatt hour of electricity. They were unveiled a year ago and set for finalization over the weekend. But on the eve of the deadline, the EPA said opposition from electric power companies would delay the rules’ implementation. While energy companies and Republican critics said the rules went too far, environmentalists had also criticized the plan for exempting existing plants and allowing a number of loopholes.