Department of Health & Human Services  Secretary Kathleen Sebelius testifies before a House Education and the Workforce Committee hearing on Capitol Hill in June  2013. (Jim Bourg/Reuters)

Secretary of Health and Human Services Kathleen Sebelius says in a new op-ed that a House oversight committee hearing in Texas on Monday is "designed to stifle, intimidate and impugn the reputation" of Obamacare navigators.

The hearing, which is being run by committee Chairman Darrel Issa (R-Calif.), will be held in Dallas and is titled, "Who are the navigators?" Navigators are people who help others sign up for Obamacare.