Senator Trotter has been under criticism since his arrest earlier this month for trying to carry a gun through a security checkpoint at O'Hare airport.
In addition to his legal problems, a recent newspaper report connected Trotter to a $1 million grant to a now-indicted police chief. Add it all up and the race is now minus Donne Trotter.
Trotter was nowhere to be found at his South Side home, but Friday, Democratic officials confirmed what many already knew.
"He feels that the Democratic Party is fractured very badly, and that could cause other political fallout down the road," said Thornton Township Supervisor spokesperson Bob Storman.
The decision to drop out of the Congressional race comes about three weeks after Trotter was arrested at O'Hare for trying to board a plane with a gun.
Trotter said he accidentally left the gun in his bag after working a security job the night before.
"I do intend on staying in the race at this time. And I'm going to continue to campaign for the people in the 2nd Congressional District," Trotter said on December 6.
But afterward, Trotter failed to garner the endorsement of Democratic committee members, despite support from powerful allies like Thornton Township Supervisor Frank Zuccarelli.
"For the sake of party unity, you have to move forward because at this stage of the game, nothing is more important than democratic unity," Storman said.
"I think he was the leading candidate," said ABC7 political analyst Laura Washington. "He would have probably gotten the democratic slate if not for the incident with the gun, and he's very well known, very well-established in his part of the district. So he had a really good shot at it."
The party still hopes to back a single candidate in an ever-widening field that includes Chicago Alderman Anthony Beale, State Senator Toi Hutchinson, former State Representative Robin Kelly, State Senator-elect Napolean Harris and former Congresswoman Debbie Halvorson.
"In a primary, you don't need a majority," said Roosevelt University professor Paul Green. "You just need the most votes. This could possibly make former Congresswoman Debbie Halvorson a player."
"The suburban turnout in the most recent election was much higher than it was in the city, so you've got a lot more suburban clout than you've ever had before in that district," Washington said.
Trotter is scheduled to speak to reporters Saturday morning. His endorsement of a candidate could still carry weight in the race.
January 3 is when candidates can begin filing petitions of the February 26 primary.