I was reading this article on Reason about the demise of Real ID, when I came across this interesting paragraph:

Wood and Molepske drafted legislation that took Wisconsin out of Real ID. Sensenbrenner, fuming, said he would travel district to district and campaign against any Republican who opposed the federal law. "I said ‘go ahead,'" says Wood. "I offered to pay for his gas." Wood and Molepske aren't feeling much heat before their September primaries; by the time Sensenbrenner made his threat, no one could mistake which way the wind was blowing.

This would be the same Jim Sensenbrenner that during his one and only debate with Jim Burkee, talked extensively about how he supported other Reupblicans, and never bad mouthed them, because they're better than Democrats.  Apparently that is unless you oppose a law which was passed with limited debate as a rider to another unrelated bill, which grossly expands federal power at enormous costs to states, invades our privacy, and will do nothing to stop terrorism.  In other words... cross Jim Sensenbrenner.