CHICAGO (Reuters) - Chicago Mayor Rahm Emanuel said on Tuesday that he would not seek re-election next year, throwing open the top job in the third-largest U.S. city after facing widespread criticism over his handling of gun violence.

FILE PHOTO: Chicago Mayor Rahm Emanuel speaks during the U.S.-China Joint Commission on Commerce and Trade Investment Luncheon Program in Chicago, Illinois, U.S., December 17, 2014. REUTERS/Andrew NellesREUTERS/

Emanuel, who has been mayor since 2011 and previously served as White House chief of staff to former president Barack Obama, was up for a third term and would have faced a crowded field of candidates in February.

“This has been the job of a lifetime, but it is not a job for a lifetime,” Emanuel told reporters in an emotional announcement at City Hall alongside his wife Amy Rule. With their three children now in college, it was time for a new chapter, Emanuel said without elaborating.

Emanuel’s announcement came the day before jury selection was scheduled to begin in the trial of white Chicago police officer Jason Van Dyke, accused of fatally shooting black teenager Laquan McDonald. Video of the 2014 shooting showed that McDonald was shot 16 times. It led to widespread protests and calls for changes within the Chicago Police Department.

“The collection of these issues has greatly soured his relationship with a core constituency fundamental to his electoral success: the black community,” said Jaime Dominguez, a professor of political science at Northwestern University.

Emanuel, who has tried to improve the city’s finances by raising taxes and fees, was facing a possible voter referendum in November to limit Chicago mayors to two terms in office.

His legacy is likely to be haunted by the video of the McDonald shooting, which led to a U.S. Department of Justice investigation of the Chicago police and findings of widespread civil rights violations. Emanuel has agreed to let a federal judge oversee reforms of the department.

Community groups have criticized the slow pace of reforms and gun violence, which is among the worst in the country.

The field of candidates for Chicago mayor includes former Chicago Police superintendent Garry McCarthy, whom Emanuel fired after the video was released, and Lori Lightfoot, who served as Chicago Police Board president.

Emanuel’s campaign committee had $7.56 million as of June 30, according to a filing with the Illinois State Board of Elections. Board spokesman Matt Dietrich said in a telephone interview on Tuesday that there was no deadline to act on the funds, and Emanuel could keep the committee active to pay campaign expenses.

If he deactivated it he could return the money to contributors or donate it, and if he ran for a state-level office he could repurpose the money for that campaign, Dietrich said.

Born in Chicago, Emanuel was a senior adviser to former president Bill Clinton. He earned millions in investment banking before serving three terms in the U.S. House of Representatives. In 2008, Obama chose him to be White House chief of staff.

“Chicago is better and stronger for his leadership, and I was a better president for his wise counsel at a particularly perilous time for our country,” Obama said in a statement on Tuesday.