(CNN) - Cross a big name off the list of possible candidates in the Chicago mayor's race.
Congressman Luis Gutierrez (D-Illinois) has decided not to throw his hat into the ring.
In a speech at the University of Illinois-Chicago on Thursday, Gutierrez said he would not seek the city's top office.
"I have unfinished business to complete, so I will not be a candidate for mayor of the city of Chicago," Gutierrez said.
The "one and only reason I'm not running," Gutierrez said, is "to continue the battle for comprehensive immigration reform."
Gutierrez, a nine-term Congressman from Illinois' 4th district, has been a champion for immigration reform - and he has made it no secret that he is frustrated with the lack of movement by the Obama administration on the issue.
Speculation about a possible mayoral bid was fueled when an internal poll by Gutierrez, released to the Chicago Sun-Times, revealed that he would be a strong candidate.
The decision by Gutierrez is good news for the potential top contenders in the race - including former White House Chief of Staff Rahm Emanuel and Cook County Sheriff Tom Dart.
Gutierrez did not endorse any candidates in his speech, but did say that he had called several of them to wish them well.