"[Weiner's] polls are probably going to go up because of his degeneracy," Breitbart said. "I don't like any of this kind of behavior."
The New York Times reported this week that Weiner's wife, Huma Abedin, an aide to Secretary of State Hillary Clinton, is pregnant.
Breitbart joined the chorus of Democratic and Republican lawmakers calling for Weiner to step down, saying such sexual messages from a public official leaves him and the office vulnerable to blackmail.
Weiner has so far refused to resign.
"Spare your constituents and spare your family," Breitbart said, admittedly enjoying all the media attention he's receiving.
He said Weiner put himself in a box by initially denying that he sent a picture of his bulging underwear to a woman in Seattle, then claiming someone hacked his account and sent the photo.
"Oh yeah, there's this huge glaring hacker," Breitbart quipped. "Why didn't they want an FBI investigation that would put me away?"
Breitbart said a week before his website, BigGovernment.com, reported the messages, they had received an e-mail indicating Weiner had been sending torrid messages to a woman in Texas.
"I put that in my 'Interesting. I'll get to that later' file," Breitbart said with a chuckle.
Weiner has reportedly been exchanging sexually charged Internet messages with at least six women.
About a week after the e-mail about the messages, Breitbart said he saw the now-infamous Twitter message Weiner sent to the Seattle woman. When he remembered the e-mail days before, the BigGovernment.com staff put two and two together — they knew they had a story.
He described watching the Seattle woman delete all her social media accounts in real-time.
"We're watching the cover-up here," he recalled.
When Weiner confessed it was him all along on Monday, that was just minutes after Breitbart spoke with reporters to clear his own name. Breitbart said it was like a dream.
"It's been all adrenaline," he said. "I had vindication running through my veins. I had to prove I was right."