WASHINGTON — A Republican-run hearing on eliminating federal regulations quickly erupted into partisanship Wednesday, as GOP lawmakers said many rules cost American jobs while Democrats insisted they protect public health, the environment and even national security.

The hearing witness, Obama administration chief regulatory official Cass Sunstein, insisted that rules are designed to protect the public and the economy, and are issued only after balancing benefits against the costs.

"Job creation is in the first sentence" of President Barack Obama's recent executive order to review all government regulations, Sunstein said.

The chairman of the Energy and Commerce investigative subcommittee, Florida Republican Cliff Stearns, went on the offensive at the outset of the hearing, accusing the Obama administration of a "rush to regulate" and basing job-killing decisions on political correctness.

He said the administration of George W. Bush objected to regulations from nearly two-dozen agencies while the Obama administration has objected to none.

Stearns said the pace of issuing new regulations has been "breathtaking" in recent years.

Stearns encouraged Sunstein to answer yes or no to his questions, cutting off his attempts to defend rules by the Environmental Protection Agency and other federal departments.

Rep. Diana DeGette, D-Colo., said that unlike the Republicans, she "would like to hear answers to some of these questions."

Defending proposed environmental rules on controlling boiler emissions and greenhouse gases, she asked Sunstein whether the rulemaking allowed comments from the public and especially from industry.

"Yes, and it continues," Sunstein said.

"Over 4,800 comments including a large amount from industry," DeGette said.

"Yes, I'm aware of the sheer volume of comments," Sunstein replied.

The Energy and Commerce Committee's chairman, Republican Fred Upton of Michigan, then accused the EPA of trying to rush through the boiler regulation and said Congress might want to extend the rulemaking time. Sunstein said a shorter time frame was ordered by a court, not the Obama administration.

Rep. Henry Waxman, D-Calif. and the former committee chairman, said the purpose of the boiler rules was to protect children from mercury and lead poisoning, and the benefit far exceeded the cost. He added other EPA proposals protected national security by reducing dependence on foreign oil.

Sunstein said "we don't have any serious question" that the EPA rules survive a cost-benefit test.

With a sympathetic ear to corporate America, Republicans are talking about fighting existing and proposed regulations that Obama and congressional Democrats prize, including limits on greenhouse gas emissions and rules to enforce last year's financial and health care overhauls.

In one of several recent business-friendly moves, Obama issued an executive order last week ordering agencies to use the "least burdensome tools" when issuing regulations and to eliminate "outmoded, ineffective, insufficient or excessively burdensome" ones.

But the examples the administration has cited are far narrower than the GOP's targets.

"A lot of what each party may want to go after is supported by some set of the public," said Peter Van Doren, editor of Regulation magazine, published by the Cato Institute, which favors limiting government's reach. He predicted numerous partisan clashes, "and in 2012 we'll have the election and see what happens."

Sunstein was testifying to the House Energy and Commerce oversight and investigations subcommittee, headed by Rep. Cliff Stearns, R-Fla. Stearns said recently that he doubts Obama and the GOP want to examine the same rules.

"Instead of him talking about it, why doesn't he just go to his federal agencies and stop them cold?" Stearns said.

Since Obama controls federal agencies and Democrats run the Senate, it will be tough for Republicans to force the administration to drop regulations the president likes. Either way, participants agree, the duel will have a distinct political flavor, with the GOP pushing for business interests' goals and Obama protecting Democratic constituencies like labor and environmental groups while also showing concern about stifling jobs.

"Clearly this White House is starting to think about 2012," when Obama faces re-election, said Gary Bass, executive director of OMB Watch, which monitors the regulatory process.

In one sign of the administration's changed sensibilities, it bowed to industry pressure Tuesday and delayed a proposal to require companies to keep separate records on workplace musculoskeletal injuries.

Rep. Darrell Issa, R-Calif., who chairs the House Oversight and Government Reform Committee, has asked about 150 companies and trade groups for suggestions on which regulations to eliminate. He has yet to release any responses, but letters obtained by The Associated Press give a taste for the rules that business dislikes and Republicans might battle:

—The Associated Builders and Contractors, representing the construction industry, has complained about Obama administration policies and rules pressuring contractors to use union workers, eliminate workplace hazards and limit lead exposure.

—The Alliance of Automobile Manufacturers, representing a dozen carmakers, favors a single national fuel economy standard over conflicting state requirements. The group is also unhappy about forthcoming rules on ethanol, fuel economy labeling and visibility out the rear of vehicles.

—The National Association of Manufacturers cites a study claiming that regulations contribute to an 18 percent cost disadvantage U.S. companies face against other major countries. They say curbs on greenhouse gases, emissions from boilers and ozone pollution combined with other rules "could cost millions of jobs and weaken an economy in a still fragile recovery."

The government issues 3,000 or more regulations a year, though most are minor, according to data compiled by the Government Accountability Office, the investigative arm of Congress. Ever since President Bill Clinton issued an executive order similar to Obama's, agencies have been required to evaluate their rules, but few are killed.

In a speech in November, U.S. Chamber of Commerce President Thomas Donahue said regulations cost Americans $1.75 trillion a year. Though he said many are necessary, he complained about a "regulatory tsunami" that is the country's "single biggest threat to job creation."

Democrats and their supporters say such claims are extreme and unfounded, underscoring the gulf between the two sides.

"Implementation of environment and health laws don't actually impose a big burden on the economy," said David Doniger, climate policy director of the Natural Resources Defense Council. "It's an unproved big lie."