In a letter released on Monday, four Democratic senators from energy-producing states have urged President Barack Obama’s administration to amend the EPA’s new source performance standard regulations.

Senators Joe Manchin of West Virginia, Joe Donnelly of Indiana, Heidi Heitkamp of North Dakota and Mary Landrieu of Louisiana requested President Obama to urge the EPA to differentiate the standards based on fuel type and establish supercritical coal generation technology as the performance standard for new coal-based technology.

They wrote:

“Our nation can continue to use coal and continue to lower emissions at the sametime. Coal-based power generation projects are being developed across the country, using state-of-the-art technologies that are laying the foundation for revolutionary advancements in power plant efficiency and reduced CO2 levels.

These advancements in technology are allowing us to modernize the existing coal-fueled fleet improving efficiency and reducing emissions, while continuing to produce low-cost electricity for homes, offices and factories.”

Adopting the proposed regulations would have the effect of preventing existing plants from making upgrades that would allow for more electricity generation with less fuels and fewer emissions, the senators wrote.