Saying that public employees have become scapegoats for the fiscal problems of U.S. states, New York City Comptroller John Liu plans to release a report on Wednesday that compares public sector salaries with those in the private sector.

Speaking at a National Institute on Retirement Security conference on Tuesday, Liu said he will "battle rhetoric with research," with a further series of reports on public employee compensation and pensions.

Wisconsin Governor Scott Walker has suggested the state close its budget gap with cuts to public employees' pay and benefits. He also has called for the end of public employees' collective bargaining rights, which has sparked demonstrations at the state capital.

"I'm happy about what they said in Wisconsin because I think it lays bare the ideological underpinnings of what's really happening," Liu said.

"A year ago it was about big corporate bonuses," said Liu about taxpayers' anger over the financial crisis and subsequent economic recession. "Now there seems to be a great deal of vitriol directed at public employees."

Liu, who manages the city's $113 billion pension funds, said eliminating collective bargaining "is rather extreme."

"Chipping away at the retirement security of public employees won't enhance the retirement security of private sector employees," he told Reuters on the sidelines of the conference.

Stock market declines drove down the value of many retirement systems' funds during the financial crisis, and most states pulled back on contributing to the funds as they faced their worst budget crises in decades. A report by Wilshire Associates on Monday said 99 percent of state retirement systems are underfunded.

The institute is a nonprofit research organization representing employee benefit plans, state and local agencies, trade associations and financial services firms.