(Bloomberg) -- Senator Joe Manchin toned down his energy bill ahead of a pivotal Senate vote on Tuesday, axing proposed changes to an environmental law that would make it harder for states to block the construction of pipelines.

The change comes amid pushback from Capitol Hill, where lawmakers from both parties have voiced concerns. Manchin, a West Virginia Democrat, is struggling to amass enough votes to pass the underlying legislation, which seeks to speed up the permitting of energy infrastructure across the US.

The now-deleted provision -- which would have put into law changes originally made by former President Donald Trump -- concerns states’ authority to vet water-quality impacts of proposed infrastructure within their borders. New York and other states have used the Clean Water Act certification authority to block projects including a Williams Cos. natural gas pipeline and a coal export terminal in Washington state.

An overhaul of the section of the law, which included a new one-year timeline for states to issue those permits and other tweaks opposed by environmentalists, wasn’t included in the latest version of the legislation.

The relevant part of the Clean Water Act, known as section 401, allows states and tribes to reject projects they deem a threat to water supplies and the environment. Section 401 has been the target of the natural gas industry and others who see it as giving states veto powers over projects with a national impact.

Manchin’s bill, which Democratic leadership and the White House promised to attach to a must-pass government funding bill in return for his pivotal vote on Democrats’ climate and spending legislation, would also require federal agencies to approve and issue all permits necessary for the construction of Equitrans Midstream Corp.’s stalled $6.6 billion Mountain Valley natural gas pipeline. 

In addition, it would speed the federal approval process for other energy projects, including electricity transmission projects seen benefiting far-flung renewable energy projects, which got a boost from the climate package recently passed by Congress.

But it remains to be seen if Manchin will get the 60 votes he needs to advance his package amid pushback from Republicans, who see the proposed permitting reform as political payback for the senator’s vote on the spending bill, and from Democrats who says the bill would roll back key environmental protections.

Read: Manchin Coming Up Short on GOP Support for Energy Permit Bill

Senator Tim Kaine, a Virginia Democrat, said Tuesday he would vote against the bill because it would green-light the Mountain Valley Pipeline, which crosses his home state, “without normal administrative and judicial review.” 

Senator Kevin Cramer, a North Dakota Republican who has voiced opposition the permitting measure, said the price for his vote was additional protections for Energy Transfer LP’s Dakota Access Pipeline, which is undergoing a new environmental analysis.

(Updates with explanation of Section 401 in fifth paragraph)

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