Ben Nelson, the chief executive officer (CEO) of the National Association of Insurance Commissioners (NAIC), will give up that job at the end of January, when his contract expires, the group announced.

Nelson, a Democrat who served as the top Nebraska insurance regulator from 1975 to 1976, was the executive vice president of the NAIC from 1982 to 1985. He served as governor of Nebraska from 1991 to 1999, and as a U.S. senator from Nebraska from 2001 to 2013.

Nelson has been the CEO of the NAIC since January 2013, and he will continue to work with the NAIC in a consulting role during a transition period, the group said.

He plans to return to private law practice in Nebraska and Washington, the NAIC said.

“I have truly appreciated the opportunity to return to the NAIC following my retirement from the U.S. Senate,” Nelson said in a statement included with the NAIC announcement.

Nelson succeeded Terri Vaughan, who left the NAIC CEO post to became dean of the business school at Drake University.

The NAIC is a group for insurance regulators. It does not directly create laws or regulations, but it develops model documents that often serve as templates for the insurance laws and regulations states do create. In some cases, state or federal laws allow for the automatic adoption of new or revised NAIC standards.

While Nelson was the CEO of the NAIC, NAIC teams fleshed out the models used to establish and run the Patient Protection and Affordable Care Act (PPACA) public exchange system, and to implement PPACA commercial health insurance product design and underwriting rules.

Nelson was more visible in NAIC efforts to shape implementation of the insurance-related provisions included in the Dodd-Frank Act, including the provisions that created the U.S. Treasury’s Federal Insurance Office (FIO) and gave the FIO a role in representing the U.S. insurance industry in international affairs. He has often spoken out against the idea of applying bank-based rules to insurers without fully accounting for the differences between banks and insurers.