(Bloomberg) — Republican lawmakers are debating a bill that ramps up President Donald Trump’s assault on wind and solar power, a worse-than-expected jolt to clean energy while providing aid for fossil fuels.

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Shares of renewable energy companies fell, while coal miners surged.

The Senate may vote Monday on its own version of a spending package that would phase out key tax incentives for wind and solar sooner than expected, and also adds a new tax. While some late additions include provisions that may help rooftop solar companies and the US panel producer First Solar Inc., the bill also includes a boost for coal used to make steel.

The plan would be the biggest blow yet from a Trump administration fixed on boosting fossil fuels and slowing, if not thwarting, intermittent renewable power. The proposed tax would threaten solar’s status as the cheapest electric source in many markets — and risk a Trump objective of reining in rising residential utility bills. Some of the proposals are more extreme than a version of the bill passed earlier by the House of Representatives.

“Should the current version of the Senate’s language be voted into law, the likely result would be a dramatic pull-in of build activity” for wind and solar, followed by a sharp decline beginning in 2028, analysts at Guggenheim Securities led by Joe Osha, wrote in a research note Monday.

Shares of renewable energy companies tumbled while coal miners surged. NextEra Energy Inc., the Florida-based utility owner that’s the biggest US developer of wind and solar projects, slumped as much as 5% in New York. Enphase Energy Inc., a solar-component supplier, slipped as much as 6.2%, while the US coal giant Peabody Energy Corp. gained as much as 4.8%.

The newly released version of the Senate’s tax and spending package, unveiled late Friday, requires wind and solar projects to be fully operational by the end of 2027 to qualify for clean energy incentives. This represents a significant tightening from the earlier proposal, which only required projects to begin construction by the end of 2025.

“Wind and solar have gone backwards from the original Senate draft,” said Derrick Flakoll, an analyst at BloombergNEF. “There’s this risk for basically any project that is beginning construction.”