Former Chicago Ald. Bob Fioretti announced Monday that he’s challenging Cook County Board President Toni Preckwinkle in next year’s Democratic primary. Fioretti made his announcement at the municipal airport in south suburban Lansing near the state line with Indiana. The Democrat did so to highlight what he calls the county’s unfair tax burden that’s driving residents away. But when pressed by reporters about whether he’d raise taxes, Fioretti was noncommittal. A spokesman for Preckwinkle’s campaign says she’s focusing on navigating the county through tough economic times.