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An apparent Donald Trump fan punched a lady in the face after the pair got into an argument about the outcome of the election at Boerum Hill French bistro Bar Tabac on Saturday evening then made a hasty getaway as staff tried to chase him down, according to witnesses who were shocked to see the whole thing play out in front of families during dinner-time.

“It’s the worst thing ever — a guy in front of kids punching a girl in the face,” said Jonas Leon, the manager who was on duty at the Smith and Dean streets eatery at the time of the attack.

The assailant was having dinner with a woman when he got into an argument about the president-elect with the two women at the table next to him after they expressed their disappointment about Trump’s victory, according to Leon.

The man asked Leon to throw the women out of the restaurant, but he refused, and instead moved the gent and his companion to a different table. The guy paid his check and exited the restaurant at 6:50 pm, but then dashed back in again — nearly knocking over a kid on his way — and slugged one of the ladies in the face, according to the manager.

“The guy came back almost running, and he started pushing some customer and the high-chair next to him with the baby because he couldn’t reach the girl,” Leon said. “Then he punched the girl.”

Leon ran after the brute, who began insisting that he was somebody important.

“You don’t know who I am!” he yelled, according to Leon.

Indeed, no one appeared to know who the man was, and they didn’t find out because the bruiser and his date managed to jump into their car and drove away before police arrived at around 7:20 pm.

A diner who did not know any of the other parties corroborated the account, and says she comforted the rattled victim after the assault.

“I went up to her and she just held me and started sobbing and said ‘What is happening? I just got assaulted,’ ” said Katie Freeman, a Boerum Hill resident who eating at the restaurant with her toddler, a friend, and the pal’s daughter at the time.

The 49-year-old victim declined to go to the hospital for treatment but filed a report with the police, who confirmed the incident and are said they are still investigating.

Leon was unable to take a picture of the license plate because his phone was inside at the time, and the couple paid in cash so there are no credit card records, but he describes the attacker as a 5-foot-6 man in his 40s with a buzz cut.

Freeman says the attack really struck a blow to her sense of safety in the largely left-leaning neighborhood.

“In my own neighborhood post-election it has felt like a liberal bubble where everyone has been grieving together,” she said. “It felt really startling and it made me feel a little less safe.”