Standard & Poor's downgrade of the U.S. government's credit rating has created something few thought possible: a bipartisan consensus in Washington.

Unfortunately for S&P, the rating firm is the one in the crosshairs. Democrats and Republicans in Congress are gearing up to put it under investigative scrutiny and do more to restrict the influence of S&P and its peers in financial markets.

Democrats are particularly angry about S&P's alleged $2 trillion mistake in estimating total federal deficits over the next decade. The firm changed the forecast at the Treasury Department's urging, but went ahead with the downgrade anyway, saying the change didn't greatly affect its analysis.

The Senate Banking Committee staff is gathering information, and "all options remain on the table," including whether to hold a hearing, according to a committee aide.

Rep. Dennis Kucinich (D., Ohio), a member of the House oversight committee, requested documents Tuesday from S&P's parent company, McGraw-Hill Cos., seeking information on whether it could have benefited financially from the credit rater's decision. Another Democrat, Massachusetts Rep. John Tierney, called on Chairman Darrell Issa (R., Calif.) to convene a hearing to investigate "the motivation and decision-making process" that led to S&P's decision.