LOS ANGELES, Calif.–Former Los Angeles Mayor Richard Riordan today ended his campaign to place on the ballot a pension plan that would move new city employees to 401(k)-style retirement accounts.

Riordan’s Save Los Angeles campaign determined it could not meet a Dec. 28 deadline for gathering about 265,000 signatures necessary to place the pension plan on the May 21 ballot.

Riordan launched his campaign early this month, saying that rising pension costs will sap taxpayer money from other essential city services. The former mayor warned that within five years, the city will only be able to afford to pay for police officers, firefighters and pensions.

Riordan is exploring “various other options to accomplish the goal of pension reform,” spokesman John Schwada said.

The former mayor told City News Service last week that he had spent between $200,000 and $400,000 of his own money on the initiative, which included paying about 500 signature gatherers.

Despite its failure to qualify for the ballot, the campaign claimed credit for raising public awareness about pension matters.

Growing pension costs in recent years have swallowed up an ever larger chunk of city budget funds. The city’s three plans are underfunded by at least $9 billion, according to the City Administrator’s Office.

Riordan’s plan was met by fierce resistance from public employee unions, including the Los Angeles Police Protective League, which challenged the former mayor to a series of debates on the issue.

LAPPL President Tyler Izen called Riordan’s plan “simplistic and costly for taxpayers.”

“We appreciate Mr. Riordan’s concern for the city’s financial status, we just disagree that this Charter change was a viable option,” Izen said.

“As I have said from day one, thoughtful analysis and real solutions are needed to address pension issues, and the League will continue to work towards those solutions with the city or anyone else who wants to roll up their sleeves and help.”

A coalition of public employee unions also recently began its own campaign to block residents from signing Riordan’s petition.

Service Employees International Union 721 member and city sanitation worker Simboa Wright said Riordan’s plan failed because it was bad for city workers.

“Richard Riordan’s scheme to make trash truck drivers, street-pavers and tree-trimmers retire into poverty has failed because the citizens of Los Angeles value the men and women who serve their community,” Wright said in a statement sent by SEIU 721. “City residents weren’t about to let a bunch of billionaires rewrite city policies.”

Riordan maintained his alarm today about the threat to city services from the rising cost of pensions.

“Remember it’s about services for the working poor, the elderly and the young, and not about union heads and former mayors,” Riordan said. “I ask the mayor, the city council, and union heads to work with me over the next several months to save the city from bankruptcy and drastic cuts to public services.”