Three top Senate Republicans have asked the Health and Human Services inspector general to look into whether Secretary Kathleen Sebelius has run afoul of the Antideficiency Act.

Republican Sens. Lamar Alexander of Tennessee, Orrin G. Hatch of Utah and Tom Coburn of Oklahoma made the request after reports that Sebelius may have been in effect fundraising for a private group to promote implementation of the health care overhaul.

The question is if such an endeavor might violate any government ethics rules or the Antideficiency Act. That law surfaces most frequently in connection with government officials spending money that was not appropriated, but it also contains language regarding voluntary services.

“These activities call into question whether appropriations and ethics laws are being followed,” the senators write. “The Antideficiency Act prohibits entering into contracts or obligations or accepting voluntary services for the United States in excess of available appropriations.”

Thursday’s letter follows a May 16 query from House and Senate Republicans to the Government Accountability Office, which routinely investigates executive branch misuse of appropriations.

“The Appropriations Clause is arguably the single most important curb in the Constitution on executive branch power. Article I of the Constitution gives Congress alone the power of the purse. This means a federal agency is dependent on Congress for its funding, and it is up to Congress to make important policy choices about whether or not to provide funds for a particular program and to fix that level of funding or set terms and conditions on its use,” Alexander and Hatch wrote in the first letter. They were joined by House Energy and Commerce Chairman Fred Upton of Michigan, Ways and Means Chairman Dave Camp of Michigan and Rep. Jack Kingston of Georgia.

Kingston is chairman of the Labor-HHS-Education Appropriations Subcommittee.