Prominent Irish-American Richard M Daley has announced he will not run for re-election as mayor of Chicago.
The decision ends a political dynasty in which a Daley has reigned over the nation's third-largest city for much of the past half century.
Mr Daley's decision not to seek a seventh term in February leaves open a job in which Chicagoan Rahm Emanuel, president Barack Obama's chief of staff, has expressed interest.
Mr Daley (68), a former state legislator and county prosecutor who was reared to assume the political mantle worn by his legendary father, Richard J Daley, from 1955 to 1976, said he had thought about the decision for months.
"I have given it my all. I have done my best," he said. "It just feels right."
A Democrat who has never sought higher office since being elected mayor in a special election in 1989, Mr Daley will surpass the 21-year tenure in office of his famous father in December.
The move came as a modest surprise, and will leave a gaping hole in Chicago's leadership, where a Mr Daley has been mayor for 42 out of the past 55 years.
Mr Obama, himself a Chicagoan, lauded Daley, saying in a statement, "He helped build Chicago's image as a world class city and leaves a legacy of progress that will be appreciated for generations to come."
Mr Daley's wife, Maggie, has been treated in recent years for cancer that has spread. She stood next to her husband, with the aid of a crutch, during a news conference at City Hall at which he took no questions.
The list of potential successors, beyond an array of local aldermen and politicians, includes Mr Emanuel, a former US congressman.
If Mr Emanuel were to jump into the race, he would have to act quickly. The deadline for filing paperwork to run falls on November 22nd. The election will be held in February.
After more than two decades in City Hall, Mr Daley leaves a long legacy - although he has had his share of detractors.
He cast himself as an urban planner intent on beautifying the city of three million as it emerged from its grimy industrial past of steel mills and slaughterhouses.
He pushed hard for Chicago's bid to host the 2016 Olympic Games but was disappointed when the effort failed, and he has come under increasing criticism on several fronts. His public approval rating sank to about one-third of respondents in a Chicago Tribune poll a few months ago.
Reuters