Frederick ‘Fritz’ Kaegi is in line to be the next Cook County assessor after unseating incumbent Joseph Berrios in the Democratic primary Tuesday night.

Kaegi secured 45 percent of the vote in a three-person race. He currently has no Republican challenger in the November general election.

The upset marks a potentially significant shift in the Cook County Democratic Party, which Berrios chairs. WBEZ’s Becky Vevea explains.