The chief of Minnesota's health insurance marketplace resigned Tuesday after facing criticism over the troubled rollout and a questionably timed international vacation. April Todd-Malmlov submitted her resignation during an emergency closed session of the government board of MNsure, Minnesota's version of the insurance exchange that's tied to the federal health care overhaul. She had been under increasing pressure over insurance sign-up problems and failed to get a vote of confidence from Democratic Gov. Mark Dayton last week. Scott Leitz, an assistant commissioner at the state Department of Human Services with more than a decade of high-level health care experience, was named interim chief executive while a search for a permanent leader is conducted.