At a press conference Wednesday morning, Dart said a run for mayor would conflict with his responsibilities as a father of several young children.
For the past several weeks, Dart has given many indications he was serious about running for mayor of Chicago and would announce his bid soon after the November 2 general election.
But Wednesday he made an about-face, as he said he revealed his personal decision around 8 a.m., when he called several other elected officials and told them.
He said he did not believe he could serve his wife, five children and the budget-challenged City of Chicago at the same time.
"I think I could be a great mayor. I think I could do great things. It's a question, what cost? And as many of you know who have children, when you have children, they don't understand things like, 'I'm going to be gone for the next month or two.' They are just wondering why their dad's no longer around," Dart said.
One analysis held that Dart was the only candidate who could have stopped former White House Chief of Staff Rahm Emanuel, who is still unannounced but actively campaigning for mayor. Sheriff Dart said his own internal polls showed him running first or second.
Dart says he just couldn't see himself doing what will be one of the toughest jobs in Chicago.
"I suppose if times were flush and the city was looking down the road at a very, very easy budget cycle coming up, you would probably sit there and say OK," Dart said. "Not that you could ever take a job for granted, but it would not be as demanding. The budget issues are things that I think anybody serious about this job would have to sit there and say to themselves, if you're planning on doing this job 11 hours a day, these issues are going to require 13 hours a day or 14."
Dart says he has no plans to endorse any other candidate for mayor. He says he'll go back and focus himself again on being re-elected sheriff.
Dart said he has five children, including a 1-year-old, a 3-year-old and a 5-year-old. He said if becoming mayor meant only spending time away from his family during the five-month election cycle, he may have considered a run. But Dart said he currently works 11-12 hours a day and gets to see his family on the weekends, indicating he believes a stint as Chicago's top official would take more time away from home.
"The amount of time and energy it was going to take to not just be elected mayor, but then to be the mayor, was going to mean that I would be less of a father. And that was not something I was willing to do to my family," he said.
Dart said he was afraid to tell his children that he wasn't running because he worried they would be so excited "they'd go to school and tell everybody."
"This is an all-consuming job and very difficult for someone with a young family," said Dart. "It became apparent that I could not do both of these things appropriately."
Dart would not rule out any future political moves.
"With public life in certain respects right now, it's too difficult. Four years from now, five years from now, when the kids get older, time will tell," Dart said.
Dart had hired consultants to guide a mayoral campaign and claimed his own polls showed him running first or second in a multi-candidate race. He says he will never regret his decision to spend as much time as possible with his family.
"To be honest with you, if I had to look myself in the mirror and said I put politics ahead of my children, I would never forgive myself. That is the one thing I could never live with," said Dart.
Mayoral candidates react to Dart's decision
The Dart decision would appear to benefit other likely candidates, including Rahm Emanuel. The former White House chief of staff refused to discuss the political implications of the sheriff's move, adding he had no knowledge of it until Wednesday morning.
"Tom Dart does not get scared. I think he made a decision based on Tom Dart's evaluation of Tom Dart," said Emanuel.
After a flurry of interest in the days after Mayor Daley announced he would not run for re-election next year, the past few weeks have seen more prospective mayoral candidates remove themselves from consideration.
Political consultant Delmarie Cobb says Dart's exit might open the door for another white candidate to challenge Emanuel.
"One of the more formidable opponents is out of the race. If you are one of the white candidates, I would step up at this point," said Cobb.
"It certainly will not hurt Rahm. I'll put it that way," said U.S. Rep. Danny Davis, candidate for mayor. "Tom Dart would have been a very desirable candidate, and so I think that may cause some candidates to re-think their position."
Mayoral candidate Gery Chico says the Dart announcement took him by surprise. But he says the announcement does not change the race for him.
"I did not hear from Tom Dart before he made his announcement but, again, I respect his decision," said Chico. "I made a commitment to get into the race because I believe in making our city better."
Dart's departure leaves a void for other candidates to fill.
In a statement, former U.S. Senator Carol Mosely-Braun said, "I am reaching out to Sheriff Tom Dart's supporters." City Clerk Miguel Del Valle said he, "looks forward to working hard to garner Dart's support and endorsement." and Alderman Bob Fioretti said Dart's announcement "will allow the public to focus on a few candidates with the talent, experience and support to be elected Mayor."
Another possible candidate, the state senator and Reverend James Meeks, declined to comment on Dart's announcement.
Meeks, Moseley-Braun, Congressman Davis and Cook County board of review commissioner Larry Rogers are on a short list for an endorsement from the Chicago Coalition for Mayor, a group of African-American clergy and community leaders. ABC7 has learned that the coalition is very close to making its choice.
