Chicago Mayor Rahm Emanuel (Ashlee Rezin/Sun-Times Media via AP )

Chicago Mayor Rahm Emanuel is in hot water over his handling of a case involving the fatal shooting by a white police officer of a black teenager last year. Graphic video of the October 2014 shooting, kept secret until just recently, depicts Jason Van Dyke, a white 14-year veteran of the police force, drawing his weapon on Laquan McDonald, an African American teen carrying a knife. Emanuel was forced to fire his city’s police chief, and now he is hearing calls for his own resignation. He has said he won’t resign.

But this isn’t the only problem looming for Emanuel. The Chicago Teachers Union, which has a decidedly contentious relationship with the mayor, is planning to hold a vote among its members this coming week for strike authorization if contract negotiations, already troubled, fail. This isn’t an empty threat, given that the union staged a week-long strike in 2012 that was largely supported by the city’s residents.

The union’s contract with the city expired last summer, and talks have been deadlocked.

The union released a statement saying that its governing body would “encourage all 27,000 active members to vote ‘yes’ for strike authorization” during a three-day vote being held Dec. 9-11 in all Chicago public schools where members work.  State law requires that 75 percent of the entire union membership approve strike authorization. In 2012, the union reported that about 90 percent of members voted to authorize their leaders to call a strike.

If the union gets its vote — and it presumably will — it cannot take to the streets immediately; state law mandates a process that requires months before a strike can actually be called. But it does represent another stress point for Emanuel.

The union president, Karen Lewis, was seen a potential challenger to Emanuel in his reelection bid this past spring — in which he was forced into an unexpected runoff — until she became ill. The union’s press release quotes her as telling union leaders:

“Teachers, paraprofessionals and clinicians have told us they are tired of the contract stalemate facilitated by the Board. CPS has rejected all of our proposals, many of which have no cost associated with them. This is unacceptable and time to show them we are serious about fighting for our profession and for the students in our classroom.”

The Chicago Tribune quoted her as saying:

“The (school) board doesn’t want us to take an authorization because they’re in chaos, let’s face it,” CTU President Karen Lewis told reporters after Wednesday’s meeting of the union’s House of Delegates.

On Wednesday, the union’s House of Delegates also approved a resolution calling for a Civilian Police Accountability Council that would provide stricter and more transparent oversight of Chicago police.

Here’s a chart on what the union said it won in its 2012 strike: