On Tuesday, U.S. Senator John Thune (R-SD) sent a letter to Attorney General Eric Holder and Treasury Secretary Jack Lew questioning the wisdom of placing Sarah Hall Ingram, the embattled former Internal Revenue Service (IRS) commissioner for tax-exempt groups, in charge of Obamacare.

“Given Ms. Hall Ingram’s position as commissioner of the IRS Tax Exempt and Government Entities Division when the targeting of certain groups began, please confirm whether Ms. Hall Ingram is a subject of the Department of Justice’s investigation into whether IRS employees broke criminal laws by singling out conservative groups for special review and inappropriate questions,” wrote Thune.

The South Dakota senator also requested that the IRS halt the implementation or enforcement of any regulations that may have been drafted under Ingram.

“Until there are sufficient answers as to her involvement, I request that the IRS refrain from issuing or enforcing any regulations that have been drafted under the supervision of Ms. Hall Ingram in her current capacity as director of the IRS’s Affordable Care Act office, which is responsible for implementing the health care law,” Thune said.

He added: “The IRS should also immediately cease work on additional Affordable Care Act regulations until the Department of Justice confirms that Ms. Hall Ingram is not a subject of the criminal investigation, Ms. Hall Ingram is removed from this office, or Ms. Hall Ingram is exonerated by an investigation by the Department of Justice.”