Lopez was first introduced to politics at the age of 18 when he became a precinct captain under the William Lipinski organization of the 23rd Ward on the Southwest Side of Chicago.

Prior to his political career, Lopez worked as a skycap for Southwest Airlines at Midway International Airport.

[8] No incumbent Chicago City Council member had been elected mayor since the 19th century, although two had been appointed to the office to fill vacancies.

[13] On October 3, 2023, Lopez announced he would run against incumbent Chuy García in the Democratic primary for Illinois's 4th congressional district.

[16][17] “We can discuss the cease-fire as soon as all the hostages and bodily remains are returned unconditionally,” he told the Chicago Sun-Times.

[18] According to his campaign website for the 2024 congressional race, he supports immigration reform that includes pathways to citizenship for undocumented immigrants, securing the borders to reduce the influx of additional undocumented immigrants, and creating "carve-outs" in Chicago's Sanctuary city policy so that certain individuals (those who "have committed sex crimes against minors, engaged in prostitution, have identified as members of a gang, or have been arrested for a violent crime") could be turned over to USCIS.