U.S. consumers who purchase private health coverage through the federal Obamacare website HealthCare.gov are likely to find only modestly higher premiums but may still have technical problems signing up, a top health official said on Thursday. "It won't be perfect," Andrew Slavitt, a newly appointed principal deputy administrator at the Centers for Medicare and Medicaid Services (CMS), told lawmakers at hearing before a House of Representatives oversight committee. "It's a bumpy process at times," he added. "I think we've got a committed team of people, though, that by and large are doing a very good job. But there will clearly be bumps."