State representative (2001–2011) In 1998, Mendoza ran for office in the 1st Legislative District with the support of the regular Democratic Organization but narrowly lost to independent progressive incumbent Sonia Silva, who was backed by House Speaker Mike Madigan. In 2000, with endorsements from Mayor Daley and the Hispanic Democratic Organization, Mendoza ran a second time to secure a position as an Illinois State Representative. At 28, she became the youngest member of the 92nd
Illinois General Assembly. She co-chaired the Conference of Women Legislators, helped establish the first Illinois Legislative Latino Caucus, and passed a bill to provide school children with breakfast. Mendoza served as an Illinois Democratic delegate in the primary elections for presidential candidates
Al Gore in 2000 and
John Kerry in 2004. In 2002, she visited the African countries of
Uganda and
Tanzania as a delegate for the American Council of Young Political Leaders. In June 2004, the
State Department selected Mendoza to represent the National Democratic Party in Brazil, where she debated the party's presidential platform.
City Clerk of Chicago (2011–2016) Mendoza was the first woman to hold the position of
City Clerk in Chicago. As the 43rd City Clerk of Chicago, Mendoza used technology to modernize and improve city services, such as an online
document management system and year-round city vehicle sticker sales. She also worked to modernize the city's infrastructure, including expanding services for
minority and immigrant communities. After her election in 2011, she managed an office that generated over $100 million annually from vehicle sticker sales. She reformed the city's vehicle sticker program from an annual event in place since 1908 to a year-round system, achieving an annual savings of approximately $4 million. She initiated the Companion Animal and Consumer Protection Ordinance, which prohibited Chicago
pet stores from selling dogs, cats or rabbits unless sourced from humane
shelters or
animal rescues.
2019 Chicago mayoral candidacy ,
Willie Wilson, Mendoza,
Gerry McCarthy,
Toni Preckwinkle,
Amara Enyia,
La Shawn Ford, and
Lori Lightfoot On November 2, 2018, a video from Mendoza's campaign became public, showing her plans to run for
Mayor of Chicago in 2019 while she was also seeking re-election as comptroller. She officially announced her mayoral candidacy on November 14, aiming to succeed Mayor
Rahm Emanuel. On December 14, 2018, another mayoral candidate,
Toni Preckwinkle, contested Mendoza's 12,500 petition signatures required for ballot eligibility, citing potential fraud and inconsistencies. However, after a verification process, Preckwinkle withdrew her challenge on December 19, acknowledging that Mendoza had secured over 13,000 valid signatures. During the early stages of her campaign, Mendoza was one of the leading candidates in both polling and fundraising. Public polls in late 2018 frequently showed Mendoza and Preckwinkle as the frontrunners. However, by January 2019, Mendoza's standing in polls fluctuated, and by February, she was not leading in any polls. Preckwinkle and Mendoza, along with several candidates were linked to Alderman
Edward M. Burke which influenced the mayoral race. She aimed to garner significant support from Hispanic voters and did receive the most support from this group in the first round of voting, although Hispanic voter turnout was notably low. In the end, she received the highest support among Hispanic voters of any candidate in the first round. However, Hispanic voter turnout was low. and
LIUNA Chicago Laborers’ District Council. In mid-February, Mendoza and fellow contender Lori Lightfoot criticized Preckwinkle for holding a women-centered campaign rally, accusing her of portraying herself as a victim in light of a scandal involving her former
chief of staff. Mendoza also critiqued another candidate,
William M. Daley, which journalist Gregory Pratt later noted had impacted Daley's campaign negatively among union members. Mendoza finished fifth in the primary election with 9.05% of the vote and did not advance to the runoff. On March 23, 2019, she endorsed Lori Lightfoot for mayor in the subsequent runoff election.
Illinois Comptroller (2016–present) Mendoza assumed office as the
Illinois Comptroller after a
special election in December 2016. Since taking office, she has focused on improving
Illinois' financial transparency and reducing its
budget deficit. She reprioritized the office's work to pay social and human service providers first and led efforts to streamline financial reporting processes and modernize accounting systems.
Bill backlog and credit upgrades Mendoza focused on paying down the state's $16.7 billion backlog of unpaid bills, focusing on those eligible for federal matching funds. By April 2021, she paid the backlog down to $3.5 billion. The backlog has stayed under $3 billion since later that year, helping usher in ten
credit rating upgrades from the
bond rating agencies. Some agencies cited her transparency reforms and monthly financial updates in their decisions, while
S&P Global noted that her assurances that Illinois would prioritize debt payments increased investor confidence.
Debt Transparency Act In her inaugural year, Mendoza spearheaded the Debt Transparency Act, which requires all state agencies to file monthly reports detailing outstanding bills, their age, and any accrued late-payment interest penalties.
Truth-in-Hiring and Vendor Payment Program Transparency Acts During her second year, Mendoza supported three further transparency measures. These included the Truth-in-Hiring Act, which mandates that governors list all employees on their payroll instead of "off-shoring" them in other agency budgets; the Truth in Budgeting Act, which requires governors to account for Late Payment Interest Penalties in their budget proposals; and the Vendor Payment Program Transparency Act, which obliges lenders to state vendors to disclose their ownership and funding sources. The Comptroller's office now publishes a monthly report showing how much money has been lent and repaid under the program.
COVID Portal and curbing collections In 2020, editorials in major state newspapers cited the transparency portal she developed as Comptroller, which tracked how Illinois spent every penny of federal
COVID-19 relief money, and urged their own states to follow her example. In 2020, Mendoza also announced that her office would stop withholding state payments from motorists who failed to pay red-light camera tickets. In 2021, she announced that her office would stop enforcing certain fines against low-income residents during the COVID-19 pandemic, including ending the withholding of unpaid fines from state income tax refunds for families eligible for the Earned Income Tax Credit, about $15 million annually.
Re-election Mendoza was re-elected to a full term as comptroller in
2018, securing nearly 60% of the vote against
Republican nominee
Darlene Senger. In 2022, she was re-elected with 57% of the vote against Republican Shannon Teresi and was the top vote-getter in Illinois, ahead of Senator Tammy Duckworth and Governor J.B. Pritzker. On July 16, 2025, Mendoza announced that she would not seek re-election in
2026. ==Personal life==