CHICAGO – The race to replace former U.S. Rep. Jesse Jackson Jr. heated up Monday when Cook County Board President Toni Preckwinkle endorsed state Sen. Toi Hutchinson over former state Rep. Robin Kelly, her onetime aide.

It's the most high-profile endorsement so far in the Feb. 26 primary, though it's unclear how the nod from the Chicago Democrat will influence voters in the heavily Democratic district that includes city neighborhoods, south suburbs and rural areas.

Nearly two dozen candidates have filed petitions to run. Other top Democrats include former Congressmen Debbie Halvorson and Mel Reynolds. The special election is April 9.