Coal and labor groups and power plant owners are suing the Department of Environmental Protection, saying the rule will cause them irreparable harm.

Coal-related interests sued on Monday to block the centerpiece of Gov. Tom Wolf’s plan to fight climate change

Joining RGGI is the centerpiece of Gov. Tom Wolf’s plan to address climate change.

The state can be a member of the Regional Greenhouse Gas Initiative once the rule that allows joining is published in the Pennsylvania Bulletin on Saturday.

Publishing the rule would make it official, positioning Pennsylvania to become the first major fossil fuel-producing state to put a price on carbon emissions.

Wolf has vetoed a similar attempt before. But this time, Republicans say they’re offering a solution.

In his veto message, Wolf said the regulation “is a vital step for Pennsylvania to reduce carbon emissions and achieve our climate goals.”

Pennsylvania moved closer this year to joining a regional program to cut emissions from power plants, despite repeated attempts to stop it from Republicans who control the legislature.

Gov. Tom Wolf is likely to veto the measure, but that won’t mean the regulation could immediately take effect.

The Wolf administration says the regulation to join the Regional Greenhouse Gas Initiative should be published now; the Republican-led legislature says it has ‘many months’ to review the rule.