The U.S. Environmental Protection Agency, under fire from lawmakers trying to stop greenhouse-gas rules set to start next month, said it will issue a second wave of carbon-emissions regulations by July, reported The Detroit News.

The EPA will propose new standards under the Clean Air Act for power plants by July and for oil refineries by December as part of an agreement with environmental groups and states pushing for further limits on emissions linked to climate change, the agency said in a statement Thursday.

The agency will begin its first phase of regulating carbon-dioxide pollution from power utilities and refineries on Jan. 2. The new rule, pushed by President Barack Obama after Congress failed to pass legislation capping greenhouse gases, is opposed by Republicans, the U.S. Chamber of Commerce and Democratic lawmakers such as Senator Jay Rockefeller of West Virginia.

EPA Administrator Lisa Jackson Thursday sought to respond to concern that the rules will burden business with excessive new costs and hurt the economy.

"These standards will help American companies attract private investment to the clean energy upgrades that make our companies more competitive and create good jobs here at home," Jackson said in the statement.

Texas Governor Rick Perry, a Republican, has said his state won't cooperate with the rules taking effect next month because they would cripple the economy. The regulations call for states to apply the carbon rules through permits, issued when companies seek to build or upgrade operations.

The EPA informed Texas Wednesday that the agency will take over regulation in the state if it fails to act.