The Obama administration is set to regulate CO2 emissions through the Environmental Protection Agency, pressurizing Congress to agree a way forward.

Last year a Supreme Court judgment held that the EPA had authority to regulate CO2 under air pollution laws. The Bush administration turned down the opportunity.

President Obama has given the EPA the green light to regulate CO2 and an announcement is expected from the regulator as early as this week.

Once the EPA's regulations are published, albeit not in force, Congress won't be able simply to sit on its hands but will instead feel pressure to introduce its own legislation.

The administration is pushing for agreement on a cap-and-trade regime by the UN climate change talks in Copenhagen in December.