Marilyn B. Tavenner, the official in charge of President Obama's health insurance marketplace, apologized on Tuesday to millions of Americans who have been frustrated in trying to buy insurance under the new health care law. Ms. Tavenner, the administrator of the federal Centers for Medicare and Medicaid Services, said that "nearly 700,000 applications have been submitted to the federal and state marketplaces" in the last four weeks. But she repeatedly refused to say how many of those people had actually enrolled in health insurance plans since the federal and state marketplaces, or exchanges, opened on Oct. 1.
