Kathleen Sebelius is on the defensive more than ever now that the White House has delayed a major provision of the law that requires larger employers to offer health insurance to full-time employees. Republicans say she has given a far too rosy picture of progress in carrying out the law. And they are demanding that she explain why people should be required to carry insurance next year if employers are not required to offer it. In her zeal to make the healthcare law work, Ms. Sebelius has tested the limits of her authority. After Congress refused to provide as much as she wanted for a nationwide campaign publicizing the new insurance options, she shuffled money between government accounts and sought cash from outside groups. She is defending herself and her fund-raising activities, even as she defends the law.