WASHINGTON (AP) — Eager to cast blame, lawmakers are preparing to grill President Barack Obama's top health official over problems with the rollout of the government's health care website.

A growing number of Republicans in Congress are calling for Health and Human Services Secretary Kathleen Sebelius to step down or be fired because of problems consumers are having signing up for insurance coverage on the government's new website.

On Wednesday, Sebelius heads to Capitol Hill to testify before a House committee, her first appearance before Congress since state-based health exchanges opened for business on Oct. 1.

Sebelius is likely to face questions about problems with the website as well as a wave of cancellation notices hitting small businesses and individuals who buy their own insurance.