Longtime Democratic U.S. Rep. Luis Gutierrez won't seek re-election next year, sources said Monday night, setting off a domino effect in Chicago Latino politics.



Cook County Commissioner Jesus "Chuy" Garcia plans to start gathering signatures on Tuesday to seek Gutierrez's congressional seat, the sources said. And 22nd Ward Ald. Ricardo Munoz plans to run for Garcia's County Board seat, they added.



The decision marks a swift change from Monday morning, when Gutierrez's campaign filed his paperwork to secure a spot on the March 20 primary ballot, and Garcia filed to seek re-election to the County Board.



Gutierrez, an immigration reform advocate with a high national profile on the issue, has been in Congress since 1993, representing the 4th District. He turns 64 next month. That long tenure has led to a lot of pent-up political ambition, and Gutierrez's retirement provides an opportunity for candidates who can quickly put together a campaign.



Also contemplating a run for Gutierrez's spot in Congress is freshman 35th Ward Ald. Carlos Ramirez-Rosa. Earlier this year, Ramirez-Rosa was dropped as a running mate by Democratic governor hopeful Daniel Biss because of the alderman's views on Israel.



"If the Gutierrez rumor is true, I will begin circulating (petitions) tomorrow," Ramirez-Rosa said in a text message Monday night. Ramirez-Rosa would have a free shot at the race, since his aldermanic seat isn't up until 2019.



But sources said that Gutierrez was planning to endorse Garcia, who in 2015 forced Mayor Rahm Emanuel into a runoff election. Garcia lost, but in recent weeks told the Tribune he was contemplating a mayoral bid in 2019.



Winning a spot in Congress likely would remove him as a potential opponent to Emanuel. Two years ago, Gutierrez backed Emanuel for mayor over Garcia and others in the field.



Gutierrez informed Emanuel of his decision Monday afternoon when the two recorded a joint radio interview in the mayor's office, said a source with knowledge of their meeting. Emanuel also joined Gutierrez for a tour of the Humboldt Park Welcome Center for Puerto Rican evacuees who departed the U.S. territory in the wake of Hurricane Maria.



Although the news was making the rounds in Cook County Democratic Party circles Monday night, Gutierrez, Garcia and Munoz weren't speaking publicly. Announcements, however, were expected Tuesday.



Time is running short for the candidates to get out and circulate nominating petitions, with a Dec. 4 deadline looming for both Congress and the County Board. Both offices require gathering less than 1,000 signatures, however, making it a doable feat for experienced politicians.



Gutierrez, a former alderman who like Garcia was part of the late Mayor Harold Washington's Rainbow Coalition, is in his 13th term in Congress.



The veteran Puerto Rican independence advocate has been a vocal critic of the Trump administration's response to the heavy damage inflicted there by Hurricane Maria in September.



The congressman visited the island to deliver food and supplies from Chicagoans. Gutierrez said people who wanted to leave should be allowed to fly to the mainland and receive help getting resettled.



Gutierrez was among a half-dozen Democrats who introduced articles of impeachment against President Donald Trump on Nov. 15.



Gutierrez was serving as 26th Ward alderman when he won a major promotion in 1992, becoming Illinois' first Hispanic congressman.



Now as Gutierrez prepares to exit the political stage, a Garcia candidacy could accentuate longstanding differences in the C-shaped congressional district that was carefully drawn to meld a diverse Latino community on the West and Northwest sides with Mexican voters on the Southwest Side.



Gutierrez was born in Chicago of Puerto Rican heritage and later lived on the U.S. island territory.