The Senate could vote as early as this week to eliminate a key rule that governs which bodies of water are subject to federal regulation under the Clean Water Act, possibly forcing President Joe Biden to issue the second veto of his presidency.

Earlier this month, lawmakers in the House passed a disapproval resolution 227-198 under the Congressional Review Act to scrap the Biden administration’s Waters of the United States rule, which designates which waters require permits for activities like construction and mining. Sen. Shelley Moore Capito (R-WV), who is championing the resolution in the upper chamber, argues the rule is burdensome to farmers and businesses and amounts to federal overreach.

“It hurts farmers, ranchers, developers, and miners. Really, anyone that wants to expand their footprint, they will put more regulatory burden on folks,” Capito said during a press conference earlier this month. “I think this is the voice of the majority of representation in the United States Senate and House, reflecting the country in its entirety.”

Lawmakers are able to move forward by utilizing a congressional tool that rescinds recently finalized rules with a simple majority vote in both chambers. Senate Democrats only hold a 51-member majority, including three independents who caucus with Democrats. Republicans need to peel off just two lawmakers across the aisle to win a simple majority. With multiple Democrats facing tough reelection prospects in 2024 and the ongoing health-related absences of Sens. Dianne Feinstein (D-CA) and John Fetterman (D-PA), it looks increasingly likely that Republicans could win enough support to send the measure to Biden’s desk.

Sen. Joe Manchin (D-WV) is expected to vote with Republicans to get rid of the regulation. It is still unclear how Sen. Jon Tester (D-MT), another Democrat in a red state, could vote. Both are among the most vulnerable Democrats up for reelection in 2024.

The White House said Biden would veto the measure if it reaches his desk, saying in a recent statement that repealing the rule would only increase uncertainty over water regulation, threatening economic growth, agriculture, and clean water in various jurisdictions. Democrats and environmental groups argue getting rid of the rule would roll back critical environmental protections for bodies of water across the U.S.

In response, Capito, ranking member of the Environment and Public Works Committee, said Congress should still act to strike down the rule despite the veto threat because, she said, “it’s the right thing to do.”

“We are telling the president, stop with the overregulation, the overburdensome rules that you put forward. Let’s get back to some reasonable, accomplishable rules and regulations,” she said.

The major question of what qualifies as a body of water under Waters of the United States has been ongoing for about 15 years, with the definition changing under different administrations. Versions of the rule were in effect during the Bush and Obama administrations. Obama expanded it in 2015, but the Trump administration lifted protections in 2020 with the Navigable Waters Protection Rule.

Many Republicans continue to refer to the Trump-era rule, which constrained the scope of waters subject to special permitting by the Environmental Protection Agency and Army Corps of Engineers. Many Democrats rallied against the rule, saying it lowered environmental standards and could cause more pollution. Federal courts eliminated the Trump rule in 2021, which is why the Biden administration revised it.

The fight over water regulations is also the subject of a pending Supreme Court case. The justices heard oral arguments on the issue in October in Sackett v. EPA and are expected to rule on the case this year.