Allen Weisselberg, who served as President Trump’s gatekeeper and financial guru for decades, has been subpoenaed to testify before a federal grand jury as part of the investigation into former Trump “fixer” Michael Cohen, a report on Thursday said.

​Weisselberg, 70, is considered a witness in the Cohen probe, but it’s unclear if he has already appeared before the panel or what questions federal prosecutors have for him, the Wall Street Journal reported. ​

​He has worked for the Trumps since the president’s late father, Fred, owned the company, and served as executive vice president and chief financial officer at the Trump Organization.

His ties run so deep that a person close to the company described him as “the most senior person in the organization that’s not a Trump,” the newspaper reported.

After Trump’s election victory, he turned over control of the company to Weisselberg and Trump’s two adult sons, Eric and Donald Jr.

Last year, Weisselberg arranged for the Trump Organization to pay a $35,000 monthly retainer to Cohen, who in October 2016 made a $130,000 payment to former porn star Stormy Daniels to keep her silence about an affair she alleges she had with Trump a decade earlier.

​Weisselberg was not aware of the payment to Daniels, whose real name is Stephanie Clifford, the newspaper said.

His name also popped up earlier this week in a secretly taped conversation between Cohen and Trump in September 2016 when they discussed a $150,000 payment to former Playboy Playmate Karen McDougal, who claimed she had a months-long affair with Trump in 2006.

Cohen on the tape said he had talked with Weisselberg “about how to set the whole thing up.”

​The Manhattan US Attorney’s Office declined the Wall Street Journal’s request for comment.

It said Weisselberg and the Trump Organization didn’t respond to requests.