Members of Chicago Fire Fighters Union Local 2 say they've been working without a contract for over 1,100 days.
They want to hire more paramedics and add more ambulances to their fleet.
The union has said they're trying to get their message across to Chicagoans and new visitors in town for the Democratic National Convention this week.
They rallied about 3 p.m. at the corner of Madison Street and Ashland Avenue, outside the DNC perimeter.
"There's one job that's not going to be done, as I'm running that I have to figure out who can fill in. Do I take a guy off a different rig? Do I request another rig come in? That all takes time; you should have your manpower there immediately," union president Patrick Cleary said.
The union applied for a permit to protest during the DNC, but said their request was denied twice. The city cited proximity and manpower.
The union also has a mobile billboard that's driving around Chicago during the entire DNC, and they rented two fire engines that will have banners on them, driving around the city, as well.
Cmdr. Marc Augustine has been a paramedic with CFD for 17 years.
He said his Little Village ambulance runs nearly 24/7.
"We don't need citizens waiting sometimes 10-15, 20 minutes, waiting for an ambulance. My family lives in this city: My parents, my wife, my children, you know, I want a better response for all of them, just like I'd want for everybody in this city," Augustine said.
More rallies are expected through Thursday.
Last month, paramedics and firefighters marched during NASCAR race weekend to bring attention to their fight.
The Chicago Fire Department would not comment on the union events around NASCAR or the DNC.
The city of Chicago's Department of Human Resources is the entity negotiating a new contract.
A spokesperson for the mayor said, "the Johnson administration continues to negotiate in good faith with the goal of settling a fair contract for our City's Firefighters."
The union president said the next negotiating session is scheduled for Sept. 5.