The plant stopped operations last year. Reopening it was a main sticking point in negotiations during a United Auto Workers Strike, but the plant still hasn't reopened.
The president of the United Auto Workers Union spoke on the matter Friday.
Governor JB Pritzker also released a statement, calling on Stellantis to "live up to the commitments it made a year ago to Illinois workers. There is every opportunity to begin the restart at Belvidere, and there is no time to waste."
ABC7 reached out to Stellantis, which said its committed to finding a solution for Belvidere, but the company provided no updated timeline.
Meanwhile, Stellantis, which makes Jeep and Chrysler vehicles, announced a number of significant leadership changes, including the timing of CEO Carlos Tavares' retirement and the departure of its chief financial officer as it struggles to revive sales in North America.
Stellantis is the world's fourth largest automaker and in September it announced that it was looking for a successor for Tavares, 66, as part of a planned leadership change. Tavares' five-year contract was a little over a year from its expiration date in 2026, but the company said at the time that it was possible he might remain in the job beyond that.
The company said late Thursday that Tavares will step down in early 2026.
Tavares has been under fire from U.S. dealers and the United Auto Workers union after a dismal financial performance this year, caught off guard by too many high-priced vehicles on dealer lots. Tavares has been trying to cut costs by delaying factory openings, laying off union workers and offering buyouts to salaried employees.
The Associated Press contributed to this report.