Senate Republicans are teeing up a handful of controversial amendments on a bipartisan energy bill that is now on the Senate floor, but they don’t appear intent on killing the overall measure.

Sen. John Hoeven (R-N.D.), a leader in the party on energy issues, said he expects all amendments to be subjected to a 60-vote threshold, which would guarantee bipartisan support for any proposal that passes. “If you get 60 votes, it should actually help the bill,” he told reporters Wednesday.

The amendment that could cause the most headaches on that front is a yet-to-be-offered Republican proposal to rescind the recent administration rule expanding the Environmental Protection Agency’s authority under the Waters of the United States rule, or WOTUS. A handful of Democrats agree with Republicans that the rule went too far. Hoeven said the amendment could get as many as 59 votes. If the proponents were to find one more supporter, then President Obama would be faced with a decision about whether to issue a veto threat.

Republicans also plan to offer an amendment to rescind the administration’s Clean Power Plan, Hoeven said. That’s a sure nonstarter with the White House and most Democrats.

Still, leaders in both parties are upbeat about the bill’s chances. Senate Majority Leader Mitch McConnell (R-Ky.) expressed optimism on Wednesday, saying at a press conference he expects to “complete the bill with bipartisan support sometime next week.”

Senate Energy and Natural Resources Committee Chairwoman Lisa Murkowski (R-Alaska), who sponsors the bill with ranking member Maria Cantwell (D-Wash.), said she is confident the bill would pass without any “poison pill” amendments.

“There are possibilities all over, energy-related and not energy-related. We recognize that anytime you have an open amendment process, stuff can happen,” Murkowski said.

The WOTUS amendment isn’t the only potential poison pill. There are at least three others that touch on topics that are more controversial than anything currently in the bill. But 60 votes is a high bar for any amendment that’s considered partisan.

Sen. Orrin Hatch (R-Utah) introduced an amendment to block the Department of the Interior’s three-year moratorium on new federal coal leases. His amendment would only allow a coal-lease freeze if Congress approves, and if the department conducts a study showing there would be no dent in federal revenue. Sen. John Barrasso (R-Wy.) called last week for an amendment blocking the department’s decision.

Hatch also introduced an amendment that would require the federal government to defer to states on hydraulic-fracturing regulations. Sen. Bill Cassidy (R-La.) introduced an amendment repealing the Renewable Fuels Standard.

Senate Minority Leader Harry Reid (D-Nev.) also said Democrats would offer an amendment that addresses the water crisis in Flint, Mich.

On the Senate floor Wednesday morning, Reid warned that Democrats “welcome the opportunity to help strengthen the bill, but we can’t allow extreme Republican ideological amendments to poison this opportunity.”

Later in the day, he seemed unfazed by amendments on controversial subjects, saying in the afternoon, “Republicans are going to offer amendments. We’re going to offer amendments. That’s what we do here. We legislate.”

Other amendments promise less controversy. Murkowski proposed amendments authorizing the expansion of two hydroelectric projects in her home state. Cassidy and Sen. Ed Markey (D-Mass.) introduced one that would allow the Strategic Petroleum Reserve to raise $5 billion for the Treasury by giving it flexibility on when it sells oil. Markey described it to Morning Consult this way: Why sell at $30 a barrel when you can wait for $40?

Sen. Mark Kirk (R-Ill.) introduced an amendment calling on Canada not to dispose of nuclear waste on the shores of the Great Lakes. Sens. Jim Inhofe (R-Okla.) and Tom Carper (D-Del.) introduced an amendment allowing the use of thermal energy in cases in which the government requires the use of renewable energy. Markey also proposed an amendment calling for the comptroller general to produce a report on the effects of lifting the crude oil export ban. And Sen. Mike Crapo (R-Idaho) introduced an amendment allowing for more civilian research into nuclear technologies.