U.S. Sen. Lamar Alexander called today for the resignation of Health and Human Services Secretary Kathleen Sebelius after weeks of problems since the rollout of the federal Healthcare.gov site for insurance enrollment.

“Expecting this secretary to be able to fix in a few weeks what she has not been able to fix during the last three and one half years is unrealistic,” the Tennessee Republican said in a news release. “It is throwing good money after bad.”

Alexander, who is up for re-election next year, is the senior Republican on the Senate Committee on Health, Education, Labor and Pensions. He said at least 1.5 million people will lose health care coverage starting Jan. 1 because their policies are illegal under Obamacare.

“If the exchange is not working, they will not be able to choose another policy through that exchange,” he said. “At some point there has to be accountability. Taxpayers have spent $400 million to create exchanges that, after three and one half years, still don’t work.”

Marilyn Tavenner, head of the Centers for Medicare and Medicaid Services, apologized at a House committee hearing today for the website’s problems, which have prevented thousands of people from being able to sign up for government-backed health insurance since the exchanges opened Oct. 1.