Initial estimates indicated the law would have a minimal effect on big company plans.
But a new report from Mercer, a major benefits consulting firm, finds that 6 percent of large employers say they're likely to drop their plans after the law is fully in effect in 2014, sending their workers into new government-sponsored insurance markets offering guaranteed coverage and, for many, taxpayer subsidies. Among small employers, one in five plans to drop coverage. While those are still small numbers, Republicans say it could be the start of a trend.
Camp also wants to know why HHS has exempted more than 100 employers, unions and insurance companies from a requirement that limits annual dollar caps on healthcare benefits.
"If this law is so great, then why are all these companies having to get waivers?" Camp asked.
HHS says the exemptions are only temporary, granted to avoid significantly higher premiums or a loss of coverage.
After months of protracted negotiations, Congress wrote the overhaul in broad strokes and left it to regulation writers in the federal bureaucracy to spell out specifics of how the components will work.
Sen. Mike Enzi of Wyoming, ranking Republican on the Senate health committee, plans to take a close look at those regulations, the instruction manual for the overhaul. His staff says he's prepared to use a little-known federal law called the Congressional Review Act to slow down or try to block elements that he finds problematic.
When Republicans were in charge in the past, they left a mixed record on oversight.
The low point may have come when a House committee delved into conspiracy theories surrounding the death of former President Bill's Clinton White House counsel Vince Foster. The death was ruled a suicide.
But Republicans can also point to successes, including the House investigation of Ford-Firestone rollover crashes and the Senate probe of the withdrawn painkiller Vioxx.