Brooklyn DA Eric Gonzalez will face the first big test of his political career when he decides whether to prosecute a Democratic state legislator for allegedly striking her 13-year-old son.

Crown Heights Assemblywoman Diana Richardson, 33, was arrested Nov. 5 for allegedly hitting the boy’s arm with a broomstick.

Activists say Gonzalez, appointed after the death of DA Ken Thompson, should recuse himself because he will need support from the popular Richardson if he runs for his seat next year.

“I think they should move it to another jurisdiction,” said community activist Tony Herbert. “They’re all a part of the Kings County Democratic Party.”

A source who has worked with Gonzalez doubted politics would be a factor.

“If he were to recuse himself, he would be doing it in order to show fairness. He would not do it in the vein of politics and any campaign,” the source said.