May 7 (Bloomberg) — The biggest holders of Chicago general-obligation bonds are diverging on the city's outlook as it stares down $590 million in extra pension payments. State lawmakers invoke Detroit as the consequence of inaction.

A month after Mayor Rahm Emanuel won the legislature's approval of a plan to stabilize two of the city's four pension systems, Governor Pat Quinn hasn't signed the measure into law, objecting to the possibility that city officials would raise property taxes. The delay is reminiscent of the political gridlock that plagued Illinois for years as its credit rating sank.

While Nuveen Asset Management and Vanguard Group Inc. say they prefer insured Chicago bonds, Wells Capital Management contends the city's economy is strengthening. Rating companies are also divided on the city as it faces almost $20 billion in unfunded pension promises. Standard & Poor's grades Chicago A+, three steps above Moody's Investors Service.