Amazing that this hasn't been posted here. Rachel Maddow has been covering this not as a slap at Christie but as an example of New Jersey bully politics.
It seems that David Wildstein, an executive at the Port Authority of New York and New Jersey (and a high school buddy of Christie), closed down two of three local access lanes from Fort Lee to the George Washington Bridge, the nation's busiest crossing, bringing traffic to a halt and turning borough streets into a parking lot. Wildstein specifically ordered that this was to be done in secret, not even informing the police about possible traffic tie ups. He chose the first day of school to do this, causing thousands of kids to be hours late for their first day.
The mayor of Fort Lee had earlier refused to endorse Christie in the Governor's race.
OK, that's bad enough, but when this was discovered, Port Authority of New York and New Jersey executive deputy director Bill Baroni claimed that it was done for a "traffic study". The problem was that Port Authority Executive Director Pay Foye said he didn’t know anything about the traffic study, and no evidence of such a study was found to exist.
Now, Wildstein and Baroni have resigned and they’ve both hired criminal defense lawyers. The whole mess is being looked at by the NJ legislature, and the U.S. Senate Commerce Committee has decided to investigate.
In addition, Christie is reported to have asked New York Governor Cuomo to rein in investigator of George Washington Bridge closure. Christie now denies this, although Cuomo's office said that it happened and reporters say that they have absolute proof of the phone call.
Here is a good timeline of the whole thing.
So it is Christie's fault? I doubt it, it's likely his underlings taking actions on their own. Are Democrats piling on in order to make Christie look bad? Sure they are.