Marilyn Tavenner seems poised to become the first confirmed administrator of the Centers for Medicare and Medicaid Services (CMS) in nearly six years after a relatively breezy hearing Tuesday in front of the U.S. Senate Finance Committee.

CMS, which works with states to administer Medicaid and to implement much of the Affordable Care Act (ACA), has been without a Senate-confirmed administrator since fall 2006. Tavenner took over as acting administrator in December 2011 when her predecessor, Donald Berwick, stepped down. She previously served as CMS' principal deputy administrator and Virginia’s health secretary from 2006 to 2010. President Barack Obama formally nominated her as CMS administrator in early February.

The position has been left officially unfilled in part because of the political turmoil around Obamacare, but Tavenner appeared to enjoy bipartisan support at Tuesday’s hearing and most expect that she'll be confirmed. House Majority Leader Eric Cantor and several Republican committee members -- ranking member Utah Sen. Orrin Hatch, Kansas Sen. Pat Roberts and Ohio Sen. Rob Portman -- voiced their support for her nomination.

“Given her long experience in the private sector, I have complete faith that she is an individual who will be able to take on the challenges that we face,” Cantor said, referring to Tavenner’s tenure as a practicing nurse and with the Hospital Corporation of America. “If there is anyone I trust to navigate those challenges, it’s Marilyn Tavenner.”

A few senators did ask Tavenner pointed questions about the implementation of the health care reform law and how her agency is working with states to ensure it goes smoothly. Hatch, for example, requested CMS to provide biweekly updates on the agency’s progress in setting up health insurance marketplaces in more than 30 states -- which Tavenner agreed to do.

The most heated moment came when Republican Sen. Richard Burr of North Carolina pressed Tavenner to explain whether the federal cost of setting up those 30-plus marketplaces and the concern that not enough people will use them to sign up for insurance immediately would lead to unexpected premium increases. Burr noted that the Congressional Budget Office had lowered its enrollment estimate from 8 million to 7 million. He cited a private actuarial study that concluded that because CMS is charging a 3.5 percent user fee to insurers both inside and outside the marketplaces to pay for their operation, some individuals would see their premiums increase by $600 in one year.

“Do you dispute that?” Burr asked. Tavenner said she had not seen the report.

“One of the problems with the ACA is nobody really understands what the cost of running the ACA will be,” Burr said. He asked Tavenner to provide the committee with regular updates on the expected premium impact of running the exchanges. Tavenner said she would, but the first report won’t likely come until August or September -- when premiums for 2014 are finalized.

Lastly, Democratic Sen. Jay Rockefeller of West Virginia questioned Tavenner about Arkansas’ plan (which Governing detailed in a recent post) to use Medicaid expansion dollars to pay for the Medicaid expansion population to buy private coverage on the marketplaces. He noted the concerns that the plan would raise the costs to the federal government by 10 percent or more because private insurance is typically more expensive than Medicaid.

“Why was that allowance made? Why was that waiver given?” Rockefeller inquired.

Tavenner stressed that CMS had only preliminarily agreed to Arkansas’ plan, and no formal application had been submitted or approved. Legislation, which is currently working its way through the state legislature, must be passed before an application can be filed. Tavenner also told reporters after the meeting that she does not expect more than a handful of states to pursue a plan similar to Arkansas’.

“No decisions have been made. No approval has been given,” Tavenner told Rockefeller.

The committee will likely hold a vote soon to officially approve Tavenner’s nomination before passing it to the Senate floor.