The report, released as the Supreme Court weighs the fate of Obama's healthcare law, was compiled by the Republican staff of the House of Representatives Energy and Commerce Committee with input from major corporations including General Electric, Southwest Airlines and American Express.

The companies, members of the President's Council on Jobs and Competitiveness, see costs rising as a result of higher taxes, fees, and bureaucratic burdens, according to the report, titled "Higher Costs, More Confusion, Less Coverage."

They also are concerned about new benefits requiring free preventive care, the removal of lifetime limits and insurance coverage dependents, and said the law created an incentive to drop employer-sponsored health coverage by imposing penalties that are much lower than the cost of insurance per employee, the report said.

The document represents the latest salvo in a growing election-year battle to influence voters over the 2010 Patient Protection and Affordable Care Act, which the Supreme Court could overturn in a ruling expected by the end of June.

The law, intended to extend coverage to more than 30 million uninsured Americans beginning in 2014 while fostering new innovations in the delivery of care that are designed to lower overall costs, is unpopular with a large number of voters.

White House spokesman Nick Papas dismissed the document as a "partisan report," while arguing in a blog posting that the healthcare law will reduce costs for businesses.

Congressional Democrats denounced the report as "misleading, inaccurate, contradictory" and produced their own list of corporate comments in arguing that reforms would not raise costs.

Political rhetoric on healthcare has been particularly sharp in the Republican-controlled House of Representatives, which has voted repeatedly to repeal or defund Obama's signature domestic policy achievement.

"The report fails to meet the standard of unbiased, fact-based investigation expected from the committee," Representatives Henry Waxman and Diana DeGette, two leading Democrats on the panel, said in a letter to the committee's top Republicans.

The Democrats accused Republicans of overlooking input from companies including Intel, DuPont and Kodak that suggested reforms would not have a materially negative impact.

The contents of the report reflect long-standing business complaints about the law's regulatory burdens, as well as Republican allegations that it will push costs higher.

"These expected cost increases directly contradict the president's claims that (the reform law) would tame the healthcare cost curve," the report's authors said.

Reform advocates contend that Americans are largely unaware of the healthcare law's contents but will tend to support the benefits it offers as they become known.

Earlier on Thursday, the nonpartisan research group Kaiser Family Foundation issued a report saying that consumers and employers can expect to receive about $1.3 billion in premium rebates from health insurers this year, as a result of the law.

(Reporting By David Morgan; Editing by Paul Simao)

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