A failed upstate New York Assembly candidate turned himself in to police after he was caught on camera allegedly stealing his rival’s campaign flyer out of a resident’s mailbox and swapping it with his own.

Republican Joseph Mastroianni was charged with petit larceny for the switch-up after surrendering to Socita Village police on Thursday.

Mastroianni, who is a member of the Rotterdam Town Board, had launched a bid for the 111th Assembly District — covering Schenectady and Montgomery counties — against Democrat and six-term incumbent Assemblyman Angelo Santabarbara.

Despite his alleged efforts to replace Santabarbara’s messaging with his own, Mastroianni lost to the incumbent on Tuesday.

The candidate was filmed on Oct. 17 by a Ring doorbell camera removing a political mailer from the mailbox of a potential voter, stuffing it into his pocket and placing one of his campaign flyers into the same mailbox.

“Bad, bad, bad,” Mastroianni said slyly in the clip while a woman laughed behind him.

The homeowner saw through the post office’s “informed mail delivery” emails that a Santabarbara campaign flyer was sent to their home the same day but was missing — and allegedly swiped by the Republican challenger, according to the footage.

Mastroianni could face federal charges in addition to the local misdemeanor as stealing mail is a federal felony, punishable by up to five years in prison.

The Scotia Village Police Department was tipped off about the alleged theft by Schenectady County Democratic Committee chairman Frank Salamone.

Salamone also filed complaints over the mail swapping with the US Postal Service, the state Board of Elections, the state police and the Schenectady County Sheriff.

He provided the agencies with the homeowner’s Ring camera footage of a mail carrier delivering the election flyer and “crystal clear video of Mr. Mastroianni later removing the mailer, folding it up and putting it in his pocket while laughing and telling his accomplice ‘Bad, Bad, Bad,’ obviously acknowledging his misconduct,” Salamone said.

The committee chair, who’s also an attorney, again called on Mastroianni to resign from his position on the Rotterdam Town Board.

“Not only did Mr. Mastroianni commit a crime on camera, but his refusal to offer an explanation for his actions … demonstrates his utter disregard for the public he claims to serve,” Salamone said in a statement Thursday.

“The Town of Rotterdam deserves to be represented by someone who is not an unapologetic thief.”

Mastroianni did not immediately respond to a request for comment Thursday.