Tucsonans are one step closer to deciding the fate of the city's pension system. A group seeking to overhaul the pension system submitted its initiative petitions to the city for verification Tuesday morning.

The Committee for Sustainable Retirement filed nearly double the minimum signatures required to qualify for the November ballot.

The group needs 12,730 valid signatures to make it on the ballot. Consultant Peter Zimmerman said more than 23,300 were turned in.

"We had a very good response from the public," Zimmerman said of the high number of signatures gathered. "They are anxious to see some resolution to this issue."

The city clerk has 20 days to process the signatures. The Pima County recorder then has 15 days to verify those results.

The group, funded in part by the Liberty Initiative Fund, seeks to let voters decide whether to switch Tucson's current guaranteed-benefit plan for non-public-safety employees to a 401(k)-type plan. Liberty Initiative is a national group seeking government pension changes, mostly through initiative and referendum processes.

Currently, retired city employees receive a fixed check each month for the rest of their lives, regardless of whether the city's investments earn enough interest to cover the benefits. Since this defined-benefit program is guaranteed, the taxpayers cover the difference. Next year the cost to taxpayers will be about $33 million.

Initiative backers say the present pension fund is underfunded by about $340 million. Because there will soon be more retirees than working employees contributing to the fund, they say the only way the city can guarantee future benefits promised to current employees is make up that deficit quickly, over the next 10 years. With fewer contributing workers, the current system is destined for insolvency, they say.

For future employees, they are promoting a pay-as-you-go retirement system where benefits are based on the performance of system investments.

Eventually, backers say, the city will save money.

But city officials contend financing the pension fund shortage could bankrupt the city well before any savings are realized. City estimates show, under one scenario, that the measure would cost an additional $24 million in the first year alone and tens of millions more over the next decade until costs finally start coming down around 2028.

Several unions are gearing up to oppose the measure this fall.

Zimmerman said as more details of the plan emerge over the next few months, the vitriol should recede.

"Once we're able to get this out to the public and they understand the issues," Zimmerman said. "This initial push of negativity will subside."

Contact reporter Darren DaRonco at 573-4243 or ddaronco@azstarnet.com