In 1975, Singer forwent running for a third term on the City Council and instead, unsuccessfully, challenged Daley in the Democratic Party primary of the 1975 Chicago mayoral election.
[4] Singer was a significant member of the Chicago City Council's small but lively minority opposition bloc that opposed the political machine on various matters.
[3] In 1972, he partnered with Jesse Jackson to lead a coalition of individuals who successfully fought to sit as delegates at the 1972 Democratic National Convention instead of a Daley-led group.
[5] Forgoing seeking another term on the Chicago City Council, in 1975, Singer unsuccessfully ran in the Democratic Party primary for mayor against Richard J.
[6][11] Metcalfe, a one-time ally of Daley, had become critical of what he alleged was racism and brutality in the Chicago Police Department.
[15] When Mayor Byrne, who had campaigned as a reformer, partnered with members of the political establishment, Singer jumped to defend her, saying, "I just view it as dealing with reality, with the fact that you can't change everything overnight".
By the mid-1980s, Singer had become a sort of power broker, with the Chicago Tribune's Paul Galloway writing that he had gone from an "outsider at City Hall to a well-connected insider who has considerable clout on a number of issues".
He worked with Vrdolyak on authoring ordinances, including a bill which required residential smoke detectors and Chicago's municipal guidelines regulating cable television.
[4] Some of Singer's former independent allies on the City Council expressed dismay that he had come to partner with Vrdolyak instead of Mayor Harold Washington.
In 1985, James Chapmen, state chairman of the Independent Voters of Illinois-Independent Precinct Organization expressed this sentiment, while still considering Singer a friend.
Noted liberal Chicago political consultant Don Rose criticized Singer as, "one of the clearest examples of a sellout".
Former independent alderman Leon Despres, however, defended Singer as simply being a liberal who chose to do lucrative legal work.
[3][4] In 1985, Singer would claim that he had endorsed Byrne as part of a deal to ease the passage of his cable television ordinance.
[3] In the 1984 Cook County State's Attorney election, Singer endorsed the Vrdolyak-supported Richard M. Daley for reelection instead of independent liberal alderman Lawrence Bloom.
[16] Singer was put under government surveillance as a target of the investigation into the scheme that led to the convictions of businessmen Stuart Levine and Tony Rezko.
In the 2008 criminal trial of Rezko, Levine testified to having taken secret recordings of conversations with Singer while cooperating with federal investigators.
[17][18] In 2009, Edward Vrdolyak was convicted for a 2003 real estate scheme involving Smithfield Properties, for whom Singer worked as a lobbyist and consultant.
Singer was tied to this matter, having consulted on the deal central to the conviction, and his involvement looked into by federal investigators.
[19][20][21] In 2017, Singer agreed to pay a $25,000 fine after he lobbied Mayor Rahm Emanuel by email without registering as a lobbyist.