'Ultimate Nightmare Scenario for Trump': CNN's Jake Tapper Explains Why Investigators' Latest Move Terrifies the President

A new development first reported on Thursday in the ongoing investigations into President Donald Trump and his closest allies could be a devastating blow for the president's defense against legal peril.

As the Wall Street Journalreported, Allen Weisselberg, one of the most senior members of the Trump Organization that isn't a member of the Trump family, was called to testify as a part of the Southern District of New York's investigation into Trump's former lawyer Michael Cohen.

CNN's Jake Tapper explained Thursday why this is such a major development in the investigation.

"The longtime chief financial officer of the Trump [Organization], Allen Weisselberg — linked to payments to women who claimed to have had sex with President Trump — Weisselberg has been subpoenaed to testify before a grand jury," Tapper said. "The 'ultimate nightmare scenario for Trump,' according to a Trump organization employee who says that Weisselberg knows 'anything and everything about Mr. Trump's finances."

Weisselberg was also mentioned this week in a recording released of a conversation between Trump and Cohen from before the election discussing a hush money payment to Karen McDougal, a former Playboy model who says she had an affair with Trump. Cohen says on the recording that he talked to "Allen" about setting up a shell company to handle the relevant payments.

Weisselberg's being subpoenaed "seems a clear sign officials are moving closer to the president's closest inner circle from his old company," Tappe said.

As CFO of the Trump Organization, Weisselberg has broad and deep knowledge of the president's financial dealings. 

Watch the CNN clip below: