Obama plans to sidestep Republican opposition to Richard Cordray by using a recess appointment on Wednesday, but McConnell said in a statement that the Senate is not in recess.

"This recess appointment represents a sharp departure from a long-standing precedent that has limited the President to recess appointments only when the Senate is in a recess of 10 days or longer. Breaking from this precedent lands this appointee in uncertain legal territory, threatens the confirmation process and fundamentally endangers the Congress's role in providing a check on the excesses of the executive branch," McConnell said.

House of Representatives Speaker John Boehner said in a separate statement: "I expect the courts will find the appointment to be illegitimate."

(Reporting By Karey Wutkowski and Richard Cowan)