The Trump administration is set to finalize Wednesday its much-anticipated rule gutting President Barack Obama’s signature plan for reducing carbon emissions from coal plants to combat climate change.

The Environmental Protection Agency will release its replacement of Obama’s Clean Power Plan with a modest rule intended to encourage efficiency upgrades at coal plants to help them exist longer and emit less pollution. The rule is not projected to meaningfully reduce emissions, and is expected to have little effect on the actions of electric utilities that are already switching away from expensive coal to cheaper natural gas and renewables without a federal regulation.

EPA administrator Andrew Wheeler is hosting a press conference to announce the rule Wednesday morning with Trump administration officials, lawmakers from coal-friendly states, and industry representatives.

The Trump administration plan, known as the Affordable Clean Energy or ACE rule, would encourage states to allow utilities to make heat rate improvements in power plants, enabling them to run more efficiently by burning less coal to produce the same amount of electricity. Under current rules, power plants must undergo new pollution reviews when they upgrade facilities, making it prohibitively expensive.