Former Chicago Mayor Richard M. Daley remained hospitalized in an intensive care unit Saturday, his law firm said.
Feeling ill, the 71-year-old Daley walked straight from a plane into an ambulance after returning to Chicago on Friday evening from a business trip to Arizona, according to a statement released by his spokesman and law firm.
His father died of a heart attack at age 74, and the former mayor has been hospitalized at least two times since 2000.
His family is visiting him between tests at Northwestern Memorial Hospital, Daley spokesman Rick Jasculca said in the statement.
Daley, the city's longest-serving mayor, was at the helm for for 22 years. He declined to run for reelection in 2011 and was succeeded by Rahm Emanuel, who had been President Obama's chief of staff.
Daley's father, Richard J. Daley, also served as Chicago's mayor, and the Daley family has reigned over Illinois politics for nearly a century.
As mayor, Daley was sharp with critics and cozy with supporters. He oversaw the renaissance of Chicago's downtown, improved City Hall's outreach with the black community, advocated for stronger anti-gun laws and reshaped the Chicago public school system.
A string of city budget deficits, though, led to a drop in his public approval ratings and an unwinding of some of his successes.
Friday's health issues came the same day Daley's nephew, Richard Vanecko, was sentenced to 60 days in jail after pleading guilty to involuntary manslaughter. Vanecko was charged in the 2004 death of David Koschman. Koschman died days after Vanecko punched him outside a Chicago bar.