Hillary Clinton didn’t jump a turnstile — but she broke the law by campaigning on the subway, an offense punishable by a hefty $25 fine or 10 days in the slammer.

MTA rules specifically state that “campaigning” on subway cars is a criminal offense, and video of her trip on the 4 train — after swiping her card five times before she could get through the turnstile — shows her glad handing and chatting up fellow straphangers.

She was accompanied on her two-stop trip Thursday by Bronx Borough President Rubén Díaz Jr, who introduced her to other riders as “the next president of the United States, Hillary Clinton.”

But the ex-first lady wasn’t ticketed for violating the obscure rule – Section 1050.6(c)1 of the subway rules — which bars in campaigning in cars but allows it stations as long as the candidate stays 25 feet away from vending machines and ticket booths.

Reps for Clinton — already on the feds’ radar for her use of a private email account while she was secretary of state — and the MTA did not immediately respond to requests for comment.