Sposato, one of seven candidates vying to replace retiring Ald. Tim Cullerton (38th), is "deeply committed to improving Chicago neighborhood schools," Lewis said in a statement.
The union decided to endorse Sposato because of his "willingness to work with Local School Councils, principals, teachers, and parents to involve the whole community in the education process," Lewis said.
Sposato said he was honored to receive CTU's endorsement.
"It has always been important to me to work to strengthen our neighborhood schools, and I look forward to continuing to work with our teachers and parents to improve the schools in the 38th Ward," Sposato said in a statement.
The other candidates in the race are Chicago City Council legislative aide Belinda Cadiz; Realtor Tom Caravette; retired city employee Michael Duda; Carmen Hernandez, a city water department investigator; Cook County Forest Preserve Sgt. Jerry Paszek and nonprofit executive Heather Sattler.
Sposato, a firefighter, supported the teachers strike in 2012, and opposed Mayor Rahm Emanuel's push to close 49 schools in 2013.
Sposato, a member of the City Council's progressive caucus, has been a consistent ally of the 30,000-member union, which has vowed to elect candidates that support its agenda, including a push to make the members of the Chicago Public Schools board elected rather than appointed by Emanuel.
The Feb. 24 election will be the the first under a new City Council map that moved most of Dunning from the 36th Ward into the 38th Ward along with Portage Park. The candidates are vying to replace Ald. Tim Cullerton, whose family has represented Portage Park and Dunning since 1973, and plans to retire in May.
Cullerton, along with the 38th Ward Democratic Organization, has endorsed Sattler, the chief operating officer of the 100 Club of Chicago.
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