The Environmental Protection Agency is poised to roll back pollution standards for fossil fuel power plants, a measure the Trump administration argues will strengthen the power grid and lower customer costs. But environmentalists say it will worsen climate change.

The EPA is expected to announce on Monday at the G20 Ministerial Meeting on Energy Abundance in Houston, Texas, a final rule repealing regulations on carbon and toxic emissions from fossil fuel plants, a source familiar with the EPA’s plans told the Washington Examiner. The action would represent one of the Trump administration’s biggest blows yet against emissions reductions regulations put in place by Democrats.