Editor's note: Edward Morrissey, a conservative, is a senior editor and correspondent for HotAir.com.
(CNN) -- A funny thing happened at the press conference staged by Anthony Weiner on Thursday to announce his resignation -- or at least a peculiar thing. Instead of sounding penitent and humbled as he did in his first presser, Weiner started off giving a stump speech. Rather than choking back tears as he did almost two weeks earlier when he first admitted that he'd lied about his online sexual activity, Weiner smiled and seemed relatively ebullient.
By the time he announced his resignation at the end, as a small group of hecklers yelled from the audience, his tone had left no doubt that Weiner considers this only a temporary setback.
Can Weiner come back? Some have questioned why he needed to resign at all, although apparently not on Capitol Hill, where a rare bipartisan consensus formed around a call for Weiner to leave.
Others caught in scandal have ridden out the rest of their terms; for instance, the FBI found $90,000 in former Louisiana Rep. William Jefferson's freezer in a probe of bribery and corruption, and he ended up convicted on those charges, but Democrats didn't call for his head as they did with Weiner. Similarly, Louisiana Sen. David Vitter was implicated in a prostitution-ring scandal, and not only didn't resign but ended up getting re-elected to the Senate.
Weiner made three mistakes that pushed Democrats and Republicans alike into demanding his resignation. First, unlike other sex scandals that take place behind closed doors and between adults, Weiner made his activities public and engaged in apparently indiscriminate online relationships. It's one thing to commit adultery or even be promiscuous, but it's another to have the erect genitalia of (presumably) the congressman floating forever on the Internet.
Second, Weiner's activities started to look less like consensual if unusual fun and more like predatory behavior. When a porn star holds a press conference to complain about getting pushed into sexual conversations, it's difficult to ignore.
Weiner's biggest sin, though, was lying about the issue -- and then getting his friends and allies to publicly defend him by lying to them as well. Fox News analyst Kirsten Powers, who briefly dated Weiner years ago and remained a good friend until he used her in this manner, wrote a devastating response after Weiner's confession that called his behavior sociopathic and misogynistic.
That betrayal more than anything else Weiner did sealed his fate and made him a pariah on both sides of the aisle in Congress. Had he remained, Democrats would have removed him from all his committees, leaving him with just the ability to cast votes from the House floor on behalf of the legislative minority, and it's unlikely that either party would ever give him floor time for speeches.
Is his career over? Not necessarily. Marion Barry came back in Washington after going to prison for a drug-related conviction to win another term as mayor, and he currently sits on the D.C. council.
Americans like to believe in redemption. If disgraced politicians spend enough time showing remorse and perform a secular penance in the form of community service or some other selfless effort, they'll usually get a second chance. Even Richard Nixon managed to rise again as an eminence grise in the Republican Party.
For Weiner, though, it might be a little more difficult. For one thing, he's not that important. Other Democrats in his district will rise to meet the challenge. Since it's a fairly safe district for Democrats -- it's been almost 90 years since a Republican won it -- his resignation will almost certainly have no impact on the party or the voters. Frankly, there's not much to miss in his departure.
Mostly, though, the problem is the childish, immature behavior that put Weiner in a position where resignation was his only real option. The kind of sexual behavior online that Weiner conducted is the kind we would expect from a teenager, not a grown man of 47 in Congress with a child on the way -- especially since Weiner seemed to focus his attentions on very young women.
Lying and accusing one's political opponents of sabotage and then getting friends to do the same by misleading them shows the kind of judgment that one normally sees on the playground, not among responsible adults. The inescapable conclusion is that Weiner is a case of arrested development, an adolescent trapped in a middle-aged man's body.
Voters will forgive transgressors who show remorse. They don't usually support the perpetually immature after they've been exposed, quite literally in this case. Weiner needs to grow up before he can come back, and he'll need to convince voters of a sudden onset of middle-aged maturity to succeed.
The opinions expressed in this commentary are solely those of Edward Morrissey.