WASHINGTON (AP) -- Republicans plan to use the investigative powers of Congress to go after President Barack Obama's health care overhaul, and they're focusing on questions uppermost in the minds of consumers:

What's it going to cost me? Can I keep the coverage I have if I like it?

Republicans can call hearings and compel testimony, and Obama has no veto power to stop them. In the House, they'll control three major committees with a mandate to poke around on health care, subpoenas available if needed. In the Senate, they'll have added leverage on two key panels, so their demands can't be easily ignored.

Republicans say they'll focus on what the new health care law will mean for Medicare and employer health plans, mainstays of the middle class.

"Oversight will play a crucial role in Republican efforts," Senate Republican Leader Mitch McConnell of Kentucky said. "We may not be able to bring about straight repeal in the next two years ... but we can compel administration officials to attempt to defend this indefensible health spending bill."

Still, Republicans would be wise to show they're serious about making improvements to the complex law. Mere grandstanding is likely to fall flat, says Danielle Brian, executive director of the Project on Government Oversight, a nonpartisan watchdog.

"If their intent is simply to point fingers and demonize the Democrats, then they are never actually going to accomplish their goals," said Brian. She said she's hearing mixed messages from Republicans, and from Democrats "an overreaction that any oversight is a threat."

The first question for the GOP is where to start. The overhaul reaches nearly every corner of society in its attempt to cover more than 30 million Americans now uninsured.

GOP lawmakers on both sides of the Capitol are clamoring to question Medicare administrator Don Berwick, who was appointed without Senate confirmation and has yet to testify before committees that oversee his program.

"This past Congress has had no oversight over the (Medicare) director," said Frank Macchiarola, Republican staff director for the Senate health committee. "He hasn't testified. The department has been unresponsive to letters from members. And it's astonishing."

Questions for Berwick: Will seniors in private insurance plans through Medicare Advantage face higher premiums because government payments to insurers are cut by the law? Will other Medicare cuts drive hospitals and nursing homes out of business? What does Medicare plan to do with new research comparing the effectiveness of selected drugs and medical procedures?

HHS officials say Berwick's views from a career as a medical doctor dedicated to improving the quality of care are well known. The overhaul strengthens Medicare, they add, and Berwick won't be shy about making that case himself when he testifies before Congress at the appropriate time.

"HHS is focused on delivering the benefits of the (law) to the American people as fast as we can through a steady, transparent implementation process," said spokeswoman Jenny Backus. "We are confident that Congress shares this commitment."

Republicans also want to grill Berwick's boss, Health and Human Services Secretary Kathleen Sebelius. They have questions about costs and benefits of the overhaul for working families.

Reps. Dave Camp, R-Mich., and Joe Barton, R-Texas, say they want to examine unintended consequences for job-based coverage, the kind that most Americans have. Camp is expected to chair the Ways and Means Committee in the new Congress, and Barton is currently the ranking Republican on Energy and Commerce.

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 health care 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.