The chairman of the House Oversight and Government Reform Committee is demanding that a senior Obama administration official testify later this month on reports that the Obamacare website was hacked.

Chairman Darrell Issa (R-Calif.) said he insists that Centers for Medicare and Medicaid Services Administrator Marilyn Tavenner testify on September 18 about those reports.

House Oversight and Government Reform Committee Chairman Rep. Darrell Issa, R-Calif. listens to testimony regarding social security and disability benefits, on Capitol Hill in Washington, Tuesday, June 10, 2014. Four Social Security judges are facing accusations they rubber-stamped claims for disability benefits, approving billions of dollars in payments from the cash-strapped program. (AP Photo/Charles Dharapak) AP Photo/Charles Dharapak

House Oversight and Government Reform Committee Chairman Rep. Darrell Issa, R-Calif., is demanding that a top administration official testify in September over the hacked Obamacare website. (AP Photo/Charles Dharapak)

Several press reports said a hacker broke into the website in July to upload “malicious software.” The Department of Health and Human Services said the server that was attacked didn’t contain any personal data, and said measures have been taken since then to boost security.

But that answer is unlikely to be enough for Republicans, many of whom have repeatedly warned that there are reasons to worry about personal information being stolen from the huge Obamacare database.

“For nearly a year, the administration has dismissed concerns about the security of, even as it obstructed congressional oversight of the issue,” Issa said Thursday. “The committee will continue to push for answers from the administration and Administrator Tavenner must testify on the subject of transparency, accountability, and information security alongside the Government Accountability Office at our September 18th hearing.”

“Additionally, just last month, the administration admitted that Tavenner, who was the senior official responsible for the disastrous rollout, experienced a similar email ‘loss’ as IRS official Lois Lerner,” Issa added.

Data security as it relates to Obamacare is likely to become a new focus for Republicans, as the next enrollment period under the health care law will start on November 15.