Senate Republicans are expressing support for ending Biden-era Environmental Protection Agency (EPA) waivers that allow California to effectively impose a nationwide electric vehicle (EV) mandate on other states.

Senate Majority Leader John Thune told reporters the chamber is still considering whether to take up three resolutions passed by the House last week that would rescind the waivers. On Monday, five Senate Republicans—including a member of Thune’s leadership team—told the Daily Caller News Foundation that the Senate should move ahead with revoking the waivers, as GOP members continue to work through the specifics.

The simplest approach would be to repeal the waivers using the Congressional Review Act (CRA). This act enables Congress to rescind recently issued regulations with just a simple majority vote. Under Thune’s leadership, the Senate has already repealed ten regulations put in place by former President Joe Biden and is set to eliminate four more Biden-era rules this week.

The Biden administration issued the EPA waivers in December 2024 during the waning days of the 46th president’s single term. The waivers “allow other states to adopt California’s strict emission standards on gas-powered vehicles,” the DCNF previously reported.

California’s “Advanced Clean Cars II” regulations aim to phase out the sale of new gasoline vehicles by 2035. Additionally, another regulation mandates that all trucks sold in California must be zero-emission vehicles by the same year, 2035, the outlet said.

The California regulations are scheduled to take effect beginning with the 2026 vehicle model year. Seventeen other states, along with Washington D.C., plan to adopt all or portions of the California Air Resources Board’s (CARB) vehicle standards—effectively giving California the power to shape national environmental policy.

“It’s [California waivers are] an existential threat to the combustion engine and transportation in America,” Republican Montana Sen. Steve Daines told the DCNF. “Thank God we’ve had the Congressional Review Act (CRA) to repeal. It was a terrible terrible regulation.”

“We’re gonna get this done,” Daines added. “We must get it done. And this is the perfect example from a procedural point where the CRA should be used to overturn a rule from the Biden administration.”

However, efforts to repeal the California waivers have encountered a potential procedural hurdle. Both the nonpartisan Government Accountability Office and the Senate Parliamentarian have determined that the waivers do not qualify as formal rules and therefore are not subject to review under the Congressional Review Act (CRA).

In a May 1 letter to Senate GOP leadership, Senate Democrats warned that moving forward with repeal efforts under the CRA would break with long-standing Senate precedent and could carry “profound institutional consequences.”

Senate Republicans expressed confidence to the DCNF that the conference would proceed in revoking the Biden-era California waivers, despite procedural challenges.

“The Biden administration was keenly aware of what they’re doing,” Republican Oklahoma Sen. James Lankford told the DCNF. “If they can control everything happening in California, they control the entire country on that and it would set off a contagion. This rule they’ve set up, we’ve got to find a way to confront it.”

“We don’t know exactly how we’re gonna deal with it,” Republican Arkansas Sen. John Boozman acknowledged to the DCNF. “I just simply don’t understand how an agency can draft a rule, claim it’s a rule, everybody assumes it’s a rule, and then GAO say, ‘it’s not a rule’. I think we’ll probably do whatever it takes to make sure that we actually get this thing passed.”