It's been nearly a year since a citizens' task force recommended how Kansas City could stabilize its pension funds, and the unions and city management remain at odds.

City Councilwoman Jan Marcason, who chairs the finance committee, told the two sides Wednesday she wants a concrete proposal within two weeks.

"We have got to get serious about getting something on the table," Marcason said.

The city's four pension plans -- covering employees, firefighters, police and police civilians -- collectively cost taxpayers more than $50 million per year and are still underfunded by more than $500 million. That's not as dire as many cities face, but Marcason said the city needs to adopt a financing solution before it becomes a crisis.

City Manager Troy Schulte said the city's labor groups would like to see the city -- meaning taxpayers -- contribute more money. But without reining in annual cost-of-living increases to retirees, he said, the burden on taxpayers eventually becomes astronomical, and there's less and less money for already-strapped city services.

"It would decimate the organization," he said.

Schulte said he still thinks there's a way to reach consensus on an amount that the city can contribute, a modest increase in employee contributions, and some reduction in cost-of-living increases to retirees, especially in bad years.

The city is also considering a second-tier retirement plan, with less generous benefits, for new employees.

Union representatives declined comment Wednesday except to say they plan to keep negotiating.

Marcason said it's crucial the city council adopt a workable approach in October, because the changes need to be built into the next budget that the council will adopt in March 2013.