A proposal to overhaul the federal process for permits to construct energy projects passed a procedural hurdle in the U.S. Senate on Monday, though several Democratic supporters said the legislation needed more work.

The Senate voted, 73-25, to advance what’s known as the permitting reform bill, despite opposition from some corners of the environmental advocacy world who are influential with Democrats. Several Democratic members said they would be pursuing major changes through the amendment process.

The measure is sponsored by the bipartisan leaders of the Senate Environment and Public Works Committee — led by West Virginia Republican Shelley Moore Capito as chair, with Rhode Island’s Sheldon Whitehouse the top Democrat — and the Senate Energy Committee’s Chair Mike Lee of Utah and ranking Democrat Martin Heinrich of New Mexico.

The loudest opponents of the bill are environmental groups, and their Democratic champions in Congress, that say the bill’s promise to promote federal permitting for renewable energy production and transmission projects is outweighed by the advantages it would provide fossil fuel production.

“We support the elements of the legislation that help accelerate needed transmission, clean energy deployment, and grid modernization,” Natural Resources Defense Council CEO Manish Bapna said in a Sunday statement. “But the current package goes too far in weakening essential environmental safeguards and public participation requirements.”

Bapna said the group understood compromise was crucial to any kind of permitting reform bill, but that the current legislation, an updated version of which the sponsors released Saturday, still fell short. NRDC would be “willing to assist” in making further changes to the measure, he added.

Oregon Sen. Jeff Merkley, a Democrat, similarly said Monday he could not yet support the bill, which he said had not been adequately vetted by either chamber of Congress, but he said he shared some of its objectives and hoped to improve it in coming days.

“Permitting reform for electrical transmission lines is essential,” he wrote. “But the current bill raises too many serious issues that require more deliberation. I will vote against the bill before us today, but I look forward to working with my colleagues to get permitting reform right.”

Democrats also raised issues with provisions they say would weaken tribal power to weigh in on proposed projects.

Nevada Sen. Catherine Cortez Masto said ahead of the Monday vote she would support the procedural measure, but would vote against final passage if tribal issues are not addressed.

“Clean, reliable electricity in this country should be cheap and accessible – and permitting reform is the best way to deliver for the American people,” she said. “But I cannot ignore the concerns that Tribes in Nevada have with this bill text… If Title III stays in this bill, I will not vote for final passage.”