The bridge scandal that has rocked the administration of New Jersey Gov. Chris Christie (R) has hurt the governor by diminishing one of his key selling points as a potential 2016 presidential candidate: Crossover appeal to Democrats.

(Mark Makela/REUTERS ) (Mark Makela/Reuters)

The latest evidence comes in a new Washington Post-ABC News national poll that shows Christie receiving low favorability ratings from Democrats. The survey also shows that Democrats are skeptical of the notion that the scandal is an isolated incident.

Just 29 percent of Democrats say they view Christie favorably, while 47 percent say they view him unfavorably. Nearly one in three (28 percent) say they hold strongly unfavorable views about the governor. Other national and New Jersey surveys have shown Christie's stock falling among Democrats, on both favorability and job approval.

Aides to Christie caused problems with traffic from Fort Lee to the George Washington Bridge in an apparent act of political retribution in the scandal. The governor says he had no knowledge of the incident and no evidence has surfaced to suggest that he did.

Still, 60 percent of Democrats say it is sign of broader problems with Christie's leadership. By comparison, 57 percent of Republicans say they view it as an isolated incident. Independents are split.

The Democratic skepticism about Christie is especially striking considering how well he performed among Democrats in 2013. He won about one in three Democratic voters last fall when he waltzed to reelection, exit polls show. The governor has long cultivated an image of being a problem-solver. He's cast himself as someone who has put results over party.

But for the first time since Christie has entered the national stage, that reputation is in doubt.

Christie sits in third place in the wide-open race for the GOP nomination, with 13 percent support. Rep. Paul Ryan (R-Wis.) leads the way with 20 percent, followed by former Florida governor Jeb Bush at 18 percent. Among strong tea party supporters, Christie performs poorly, pulling just 6 percent support. Even before the bridge scandal, there had been deep skepticism about him on the right, so that's not surprising.

As we've written, there is no other Republican, save Bush, with a demonstrated ability to pull moderates and Democrats like Christie. But if the bridge scandal damages that ability in the long term, Christie's chief selling point may no longer be his electability.

It's far too early to declare that to be the case, of course. But it's a reminder of how quickly things can change in politics.