Senate Republicans are working hard to convince members of their own party to finally overturn a Barack Obama-era rule to limit methane leakage, but it's not clear an agreement can be reached by next week.

House Republicans in February easily passed a measure that would roll back a 2016 Department of Interior regulation limiting methane emissions from oil drilling sites located on public lands.

The Senate GOP majority had been expected to clear the measure for President Trump's signature, but the effort hit a snag when a group of Senate Republicans from corn-growing states withheld their support. Those senators first want a guarantee that the Senate will pass legislation waiving a regulation that restricts ethanol use during the summer months.

The four senators, who include Sen. John Thune, of South Dakota, the number-three GOP leader, and Judiciary Committee Chairman Chuck Grassley, of Iowa, sought to include the waiver in the just-passed 2017 spending bill, but the provision was excluded.

That means they still oppose the methane language, and time is running out for the GOP to use an expedited process to repeal the methane rule.

The Congressional Review Act allows Congress to quickly repeal federal regulations with a simple majority in both chambers. But it only applies to regulations enacted within the past 60 legislative days.

The deadline for repealing the methane rule is May 11.

Senate Majority Whip John Cornyn, R-Texas, said a deal may still be reachable. He said the hold-out Republicans have been promised a hearing on ethanol waiver legislation in the Senate environment committee.

But spokespeople for both Grassley and Thune would not say whether they would agree to the deal.

Grassley last week rejected a proposal for the ethanol waiver to be handled through the Trump administration. Grassley spokesman Michael Zona told the Washington Examiner that Grassley is "looking for the best legislative vehicle" for the ethanol waiver.

Cornyn said he is not certain whether a deal can be reached.

"I think it's still in the process of being discussed whether that is adequate for the corn state Senators," Cornyn said Friday. "But I'm optimistic."

While Republicans struggle to finish that issue, they have a few other pieces of business to handle next week when the House is out. One of these is a vote to confirm former Rep. Heather Wilson, R-N.M., to serve as Secretary of the Air Force, and another is consideration of Scott Gottlieb's nomination to serve as commissioner of the Food and Drug Administration.

Behind the scenes, Senate Republicans are also expected to begin drafting a healthcare reform bill now that the House has approved its own legislation on May 4 to repeal and replace Obamacare.