CHICAGO (CBS) — Tuesday was the last day to file objections to the nominating petitions of the 20 candidates in the race for mayor of Chicago.

As CBS 2’s Vince Gerasole reports, campaign volunteers and some candidates themselves have been working for the past week to comb through nominating petitions to make sure every signature is legitimate.

To run for mayor, a candidate must file the signatures of 12,500 registered voters in Chicago. Candidates typically file many more than that, in case of problems with any signatures.

It is up to a candidate’s opponents, not the Board of Elections, to challenge the legitimacy of nominating petitions.

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The deadline passed at 5 p.m. Tuesday to challenge the nominating paperwork for any of the candidates for mayor.

It all happened with more than a little showmanship as campaign workers rolled in and hoisted up mountains of campaign signatures meant to qualify a candidacy.

Petition watcher Aldolphus Kindle said “our eyes are watching.”

Kindle said it’s a long and tedious process because of the thousands of signatures each candidate files.

“My eyes are ready to drop out,” he said, adding that he’s been reviewing signatures since before Thanksgiving.

“I haven’t taken a day off. In fact at my thanksgiving table we were verifying signatures,” Kindle said.

Dozens of city computers allow petition signatures on paper to be compared with those on file from voting records.

When signatures match up, there’s no contest, so campaign workers look for fake names, fake addresses, or names that don’t match the address of the registered voter.

Kindle said that on one petition, it appeared that “they took the phone book and went in alphabetical order and wrote them in.”

He also said he’s come across some amusing fake names on petitions, like one person who signed “Casper the Friendly Ghost.”

“That happens a lot,” Kindle said

Another petition watcher, Lavoris Smith, said some people give addresses that can’t possibly exist, such as addresses that would be in the middle of Lake Michigan.

“You can’t live in the lake. So you have to put two and two together,” Smith said.

“It is only in Chicago that elections are a blood sport and we enjoy every minute of it,” Kindle said.

Former White House chief of staff Rahm Emanuel already has plenty of opposition to his bid to replace retiring Mayor Richard M. Daley.

According to the Chicago Board of Election Commissioners, Emanuel had 21 challenges filed against him as of Monday. Hearings on candidate challenges are set to begin next week.

Opponents contend Emanuel isn’t eligible to run for mayor because he worked for nearly two years as chief of staff before quitting in October to return home to run for mayor. His campaign calls the residency challenges a frivolous distraction.

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