CHICAGO (CBS) — The city could soon know whether Chicago Public Schools teachers are going to authorize a strike, but the teachers are already crying foul.

As CBS 2’s Mike Puccinelli reports, the Chicago Teachers Union has filed a complaint with the Illinois Education Labor Relations Board. They say an 11th-hour letter sent to teachers by CPS chief executive officer Jean-Claude Brizard was an unlawful attempt to influence the vote.

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CTU president Karen Lewis is now appearing in a new radio spot, lashing out against CPS administrators.

“For months, Chicago’s parents, educators and community have been bullied and bullied,” Lewis says in the radio spot. “We must fight these out-of-town reformers who know nothing about public education.”

The spots, which began airing this week, encourage the more than 25,000 teachers to vote to authorize a strike at a later date.

“Strikes aren’t good for anyone. Our vote is a necessary step in getting the schools our children deserve,” Lewis continues in the radio spot. “Our children can’t wait any longer.”

The voting at more than 600 schools has been taking place since Wednesday. That is despite a call from Brizard to delay the vote until the last week in August.

He made that call in a letter e-mailed to all of the system’s teachers on the eve of the vote. In his letter, he called the union’s representations of the administration’s positions misleading.

“Teachers are being asked today to make a decision based on incomplete, and very often grossly inaccurate, information,” Brizard said. “We’re in the middle of negotiations. Why do it now?”

Brizard has advised teachers to wait until an independent fact-finding panel issues a report that could serve as the basis for a contract compromise.

Brizard said the vote was rushed by the union. He said the authorization vote would have been more appropriate if it had been held in the last week of August. That way, Brizard says, retiring teachers wouldn’t have voted Wednesday on a deal that he says won’t actually affect them.

But teachers say the motivation for taking the vote now is that a successful vote to authorize will give them leverage as the negotiations continue.

“Why wait? Why wait?” Lewis said. “We can’t wait.”

Negotiations began in November, but the two sides remain far apart. After voting, Lewis – a former math teacher – explained up her demand for a 29 percent pay hike, given the push for a longer school day, and the Board of Education’s decision not to give teachers promised raises last year.

“Our workday has increased 20 percent, so we asked for that. They stole 4 percent from us last year, we asked for that. And then we want a 5 percent raise next year,” she said.

But the district says it simply cannot afford a 29 percent pay hike, and is offering 2 percent hikes instead.

To authorize a strike, 75 percent, or more than 19,000, of all Chicago Teachers Union membership must vote yes on a strike. That alone would be a resounding rebuke for CPS leadership.

If the vote is successful, the city’s teachers could later walk off their jobs for the first time in 25 years.

At this point, there has been no response from the Illinois Education Labor Relations Board on the teachers’ complaint.

Meanwhile, we likely will not know the results of the vote until next week.