CHICAGO (CBS) — Shortly before the polls closed Tuesday, State Sen. Martin Sandoval (D-Chicago) filed a challenge to the results in the 21st District Illinois House race, alleging fraud by election judges.

Sandoval claims the problems are centered in the 22nd Ward. He claims that judges who back Democratic candidate Rudy Lozano gave Republican ballots to voters known to be backing challenger Silvana Tabares. However, no Republican candidates were running in the 21st District.

LISTEN: WBBM Newsradio’s Bob Roberts reports

Chicago Board of Election Commissioners spokesman Jim Allen has seen the 23-page complaint, but is saying little.

“We just received this a little while ago. We really can’t comment on pending litigation,” Allen said. “At this point, we’re focused on counting all the ballots and reporting the results, and then we’ll certainly address any and all concerns relating to any kind of election pranks from there.”

Overall, given that it was the first election in the city following redistricting, Allen said voting went “extremely well.”

Only one of the city’s 2,369 precincts opened late, and Allen said voters who could not vote early at the one precinct were able to do so before 7 p.m., so there was no need to obtain a court order to allow it to remain open later.