Republican and some Democratic lawmakers are jockeying to kill or alter EPA regulatory authority that began taking effect in January on controlling carbon dioxide pollution blamed for global warming.

Senate Majority Leader Harry Reid had been aiming for votes early on Wednesday on the proposed EPA amendments, which individual senators are trying to attach to an unrelated small business jobs bill.

But he now says he is aiming for sometime Thursday or Friday on the controversial measures, after some senators slowed down the process.

The Obama administration, backed by some Democrats and environmentalists, supported the EPA’s increased authority after Congress last year failed to pass legislation dealing with climate change.

Republicans are sharply opposed, arguing that new energy regulations would increase business costs at a time when the U.S. economic recovery is fragile.

Some Democrats, especially those from coal-using or coal-producing states and who are up for re-election next year, have expressed concerns, as well.

There could end up being four votes on various EPA-related proposals, and all of them could fail. Nonetheless, the Senate’s votes could further undercut international efforts to control global warming if a simple majority of the 100-member Senate votes in favor of any of the measures. Sixty votes will be needed to pass any one of the proposals.

* Senate Republican leader Mitch McConnell is pushing a bill to completely strip EPA of its authority to regulate carbon pollution under the Clean Air Act.

* Democratic Senator Jay Rockefeller is proposing a two-year delay in EPA regulation.

* Senator Max Baucus, also a Democrat, would exempt all agriculture operations from regulation, as well as any small operation -- one that emits less than 75,000 tons of carbon a year. The EPA says it only wants to focus now on large factories, oil refineries and coal-fueled electric utilities.

* Democratic Senator Debbie Stabenow would suspend EPA regulation for two years but also create a single national standard for motor vehicle emissions. That could hobble California’s attempts to impose tougher standards than the rest of the country after 2016.