Resistance from legislatures within both parties could make President-elect Joe Biden’s promise to end U.S. fossil fuel subsidies hard to keep, according to Reuters.

The subsidies are worth billions of dollars a year to drillers and miners. Biden has said getting rid of them will generate money to pay for his $2 trillion climate plan.

However, reforming tax breaks that allow companies to produce oil, gas and coal more cheaply will require Congress to pass legislation. Gaining enough support to do so is likely going to be a challenge for the Biden administration.

Learn more: Reuters > Biden plan to end U.S. fossil fuel subsidies faces big challenges