Jensen Ackles and Jared Padalecki Jensen Ackles and Jared Padalecki

Upset that the CW has pulled tonight's episodes of Supernatural and Smallville at the last minute? Blame Chicago politics.

The CW decided to repeat Thursday night's episodes of The Vampire Diaries and Nikita after learning that at least two major markets — Chicago and Baltimore — were pre-empting the shows. In Chicago, CW station WGN is airing a Chicago mayoral debate, which will likely draw increased interest due to the drama over candidate Rahm Emanuel (whose eligibility has been called in to question). In Baltimore, a college basketball game is pre-empting the shows.

This also represents the first week that an original Vampire Diaries faced off against Fox's American Idol steamroller. Given that fact, and the major market preemptions, the CW decided to give the shows an extra one-week promotional boost.

The Smallville and Supernatural episodes scheduled for tonight will now run next week, on Feb. 4.

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