A Republican senator in a tight re-election race charged Thursday that Obamacare has essentially committed consumer fraud by over-promising and under-delivering, and said the federal government would investigate the program if it were a private insurer.

Sen. Ron Johnson, R-Wis., who is trailing opponent Russ Feingold in RealClearPolitics' polling average by double digits, led a Thursday hearing of the Senate Homeland Security and Governmental Affairs Committee. He wondered in that hearing whether Obamacare would be investigated by federal agencies for misleading consumers.

Johnson said the Federal Trade Commission or other agencies would investigate any insurer that made similar claims about Obamacare, including President Obama's pledge that if you like your doctor you can keep him or her.

"When it is passed by the federal government it becomes legal consumer fraud," he said.

Johnson was joined by other GOP senators in their critique of the law, including many who are also facing re-election this year.

"I remember the victory dance that [Democrats] performed after passing Obamacare without a single Republican vote," said Sen. John McCain, R-Ariz.

McCain was responding to calls from Sen. Tom Carper, D-Del., for bipartisan work to fix the Affordable Care Act. He said that Democrats forced the law "down our throats" and now wanted help to fix it.

McCain cited competition issues in his home state of Arizona, where 14 out of 15 counties will only have one Obamacare insurer. McCain is up about 13 points in his re-election race, according to RealClearPolitics polling average.

Carper argued that the Affordable Care Act has drastically expanded care to Americans. He pointed to Washington state, which reduced the uninsured population by 50 percent since the law went into effect.

But Sen. Rob Portman, R-Ohio, said in response that many of the "pledges and promises that have been made just haven't been kept. For a lot of my constituents, it is not an improvement."

Portman noted the recent collapse of an Ohio consumer oriented and operated plan created by the administration to spark more competition on Obamacare's exchanges. The co-op collapse means about 22,000 people have to find new coverage.

Portman has started pulling away in his re-election race against former Gov. Ted Strickland, with RealClearPolitics' average showing him up ahead by 13 points.