Marilyn B. Tavenner, the former Obama administration official in charge of the rollout of HealthCare.gov, was chosen on Wednesday to be the top lobbyist for the nation’s health insurance industry.

Ms. Tavenner, who stepped down from her federal job in February, will become president and chief executive of America’s Health Insurance Plans, the trade group whose members include Aetna, Anthem, Humana, Kaiser Permanente and many Blue Cross and Blue Shield companies.