Mark Sanford is back, proving that scandal doesn't have to be a knockout blow in politics.

That sounds like good news for Anthony Weiner, the disgraced former congressman thinking about his own comeback. But the reality is that if Weiner runs for mayor of New York, he would likely face more difficult challenges.

(Alex Wong/Getty Images)

The former governor's victory illustrates that when the fundamentals are very friendly, coming back is doable. In the case of Weiner, they are not as accommodating.

When it comes to Sanford, the stars seemed to align to create a way back into politics for him. Here was 1) A House seat he once held with 2) No other top tier Republican candidates, in 3) A district with a strong fiscal conservative bent, for 4) A job with a lower-profile than the one he left under a dark cloud.

That's not to say Sanford was on pace to to waltz to victory from day one. He wasn't, and didn't. Sanford's margin of victory doesn't show the bumps and bruises aplenty he absorbed against Democrat Elizabeth Colbert Busch. Because of his baggage, it was a tough race, and in the end, a hard-fought win.

But it's hard to argue that it wasn't the opportunity for Sanford to try to make a comeback, if he was ever going to make one. The same can't be said of Weiner.

For starters, Weiner would be aiming very high. Being mayor of New York City is one of the highest-profile political positions in America. It's a step — if not several — up from where he was in Congress. We're not talking about a comeback of baby steps here. It's hard to ask voters for what would essentially be a promotion after resigning under a dark cloud.

Secondly, Weiner wouldn't have the benefit of being an immediate front-runner for his party's nomination. That title belong to Christine Quinn, the City Council speaker whose formidable infrastructure will be tough to match and who, polls show, has jumped out to an early lead.

The same polls show Weiner running second, which is certainly not a bad position to be in considering where he is coming from. But again, Weiner would be walking into more difficult terrain, compared to Sanford. And he would be doing so with a high number of voters holding an unfavorable view of him, the survey data show.

As we've written, there is another lesson for Weiner in Sanford's experience: It’s not just what’s already out there that you have to worry about. Jenny Sanford's complaint that the former governor trespassed on her property was an unexpected development that reminded voters about their divorce, and by association, about Sanford's 2009 disappearance from the state to visit his then-mistress.

For his part, Weiner has said he "can’t say that [reporters] are not going to be able to find another picture or find another person who may want to come out on their own." If they did, it would be bad news for him.

All that said, there are things working in Weiner's favor. He has deep roots in New York City politics. He served on the New York City Council. He has millions leftover in his campaign account he could spend. He knows how the system works and he's well-known to voters.

Weiner would definitely have a chance if he runs. (He wouldn't be considering as running so closely if he didn't.) But it would be tough. And based on the fundamental contours, the challenges out of the gate would be bigger than they were for Sanford.