Six U.S. states, led by Massachusetts and California, are taking steps to put public pension overseers in charge of retirement savings plans offered to nongovernment workers, according to an advocate of the idea.

Massachusetts, California, New York, Florida, Ohio and Connecticut have made or are actively considering such moves, said Hank Kim, executive director of the National Conference on Public Employee Retirement Systems, a trade group in Washington that backs letting government fund managers control retirement plans set up for nonprofit organizations and small businesses.

"It's beginning to be acknowledged that while the 401(k) is part of the private-sector retirement puzzle, it cannot be the only part," Kim said during a meeting of the Information Management Network's Public Funds Summit near San Diego.