IRS building

The head of the U.S. Internal Revenue Service should resign due to the agency’s inability to improve its defenses against hacks on taxpayer data, a Republican lawmaker said on Friday.

Republican Representative Barbara Comstock said new leadership is needed to replace IRS Commissioner John Koskinen due to failures to secure Americans’ sensitive information from malicious intrusions, escalating a line of attack from Republicans who frequently criticize the federal tax collection service.

“Commissioner Koskinen has provided little confidence that cyber security is a top priority at the IRS,” Comstock said in a statement shared with Reuters, adding she was concerned the agency apparently has no one in charge of cyber security.

The IRS did not immediately comment.

More than 700,000 individuals may have had their personal information pilfered by hackers during an intrusion last year, the IRS announced in February. That number has been repeatedly revised upward from initial estimates that were far smaller.

Koskinen is not the first Obama administration official to be targeted by Congress for his handling of cyber security. Last year Katherine Archuleta, head of the Office of Personnel Management, resigned after several lawmakers from both parties called for her ouster following the theft of personal data of more than 21 million individuals.