When Congress returns in September from its monthlong recess, House Republicans say they will pick up where they left off in crafting and passing legislation to restrict U.S. EPA's air quality rules.
But Senate Democrats say they expect to have no trouble killing those proposals from the GOP-controlled House.
"They keep trying to do that," said Environment and Public Works Chairwoman Barbara Boxer (D-Calif.). "They keep trying to overturn the Clean Air Act, the Clean Water Act, the Endangered Species Act. That's not going to happen."
The House has already approved several bills this year to reduce EPA's authority, including one (H.R. 910) in April that would prevent the agency from regulating greenhouse gas emissions from stationary sources, such as power plants.
A fiscal 2012 appropriations bill (H.R. 2584) that was yanked from the House floor this week would have placed additional temporary restrictions on EPA rules, including for greenhouse gas emissions from vehicles and for hazardous and soot- and smog-forming emissions.
Rep. Ed Whitfield (R-Ky.), who heads the House Energy and Power Subcommittee, said Monday that his panel may take on EPA's rules for ozone and hazardous emissions from utilities and from the manufacture of cement when Congress returns in September.
But Boxer said such bills would be dead on arrival in the Senate.
"We've had those fights before and we've beat them before and we'll beat them again," she said, adding that polls showed that Americans favor more environmental safeguards, not fewer.
Sen. Ben Cardin (R-Md.) was similarly optimistic, adding that even if House Republicans try to attach EPA restrictions to must-pass legislation -- such as a spending bill for fiscal 2012 -- they would not be successful.
"I'm opposing the anti-environmental riders," he said, adding that changes to environmental law "should come in through the substantive committees, they shouldn't come in through the appropriations process."
He agreed with Boxer that the Environment and Public Works Committee would not pick up anti-regulatory bills.
Sen. Tom Carper (D-Del.) said that as long as EPA comes out with an ozone rule that it can demonstrate will provide more in savings than it costs, the Senate is unlikely to pass legislation to knock it down.
"I think they'll be on safe footing, especially if there's a positive cost-benefit analysis," Carper said.
But the Senate's Republican critics of EPA regulation said they will continue to pursue rollbacks to EPA regulation in the fall.
"We're going to continue to fight them every step of the way," said Sen. John Barrasso (R-Wyo.), who earlier this year introduced legislation (S. 228) that would prevent any federal agency from implementing programs linked to climate change.
Barrasso said he will look for ways to use the Congressional Review Act to combat EPA regulations and will continue to forge alliances with Democrats who have been skeptical of the agency's activities.
"I'm not stopping," he said.
Meanwhile, Sen. Lisa Murkowski (R-Alaska) said the House EPA and Interior spending bill will inform the counterpart measure she will help craft as the top Republican on the Senate Interior and Environment Appropriations Subcommittee, though she said the Senate bill would not go as far.
"I think you can look at what the House has done," Murkowski said. "You can use that as a guide -- those are the markers that they have clearly laid down. I don't think you're going to see that level of activity in terms of riders on the Senate side."
Murkowski has been critical of several EPA rules, especially current and future plans to regulate greenhouse gas emissions under the Clean Air Act.
But she said that only a few select policy riders would be included in her committee's bill.
"Even though I'm the ranking member doesn't mean I get everything I want on the committee," she said. "So we're looking at this very critically, figuring out those initiatives that will really kind of take that precedence."
The Interior and Environment spending bill is expected to move as part of a larger omnibus spending package or continuing resolution when Congress returns next month, which may further limit the policy provisions in the final bill.