Federal officials disclosed Thursday that they want to enter settlement talks with an environmental group that sued the government over the potential climate change impacts from burning coal mined in Western states.

Government attorneys have asked judges overseeing the cases to put them on hold until April 1 while negotiations take place, according to court documents and U.S. Justice Department spokesman Wyn Hornbuckle.

The projects combined involve more than 600 million tons of coal that companies are seeking to mine in Wyoming, Utah, Colorado and New Mexico.

Most of the fuel would come from Arch Coal, Inc.’s Black Thunder Mine in eastern Wyoming, one of the largest coal mines in the world. Arch declared bankruptcy earlier this year, but the mine continues to operate.

WildEarth Guardians, the group that sued to overturn federal approval for the projects, has prevailed in similar cases challenging mining projects in Montana and Colorado. As a result, the Interior Department was forced to re-analyze the impacts of mining and burning coal. No mining operations were halted.

“We’re not trying to shut everybody down tomorrow, but Interior needs to understand there are some consequences here,” said WildEarth Guardians’ Jeremy Nichols.

The move to settle the still-pending lawsuits comes after Interior Secretary Sally Jewell last month imposed a moratorium on new sales of taxpayer-owned coal reserves.

There has been longstanding criticism of the government’s coal program by some members of Congress. Jewell’s Jan. 15 order called for a three-year review to address climate change impacts and determine if taxpayers are getting a fair deal in the sale of public reserves to private companies.

Hornbuckle declined to say if the request for settlement talks in the WildEarth Guardians lawsuits was tied to the moratorium.

Attorneys for the mining companies involved in one of the lawsuits asked U.S. District Judge William Martinez in Colorado to let them intervene in the case so they could participate in settlement discussions.

Besides Arch’s Black Thunder, the mines in that case are Cloud Peak Energy’s Antelope Mine in Wyoming, Bowie Resources’ Bowie No. 2 mine in western Colorado and Peabody Energy’s El Segundo Mine in northwestern New Mexico.

Two other lawsuits involve New Mexico’s San Juan Mine, which was recently sold to Westmoreland Coal Co. and the Flat Canyon coal lease near Bowie Resources’ Skyline Mine in Utah.