Donald Trump Jr ‘clearly has something big to hide’ from the Republican senators who subpoenaed him: Former CIA official

The former chief of staff at the Central Intelligence Agency (CIA) predicted that Donald Trump, Jr. is hiding something "big" from Congress.

Jeremy Bash was interviewed Wednesday by guest anchor Steve Kornacki on MSNBC's "The 11th Hour."

The host asked for the odds of Trump, Jr. actually testifying before the Republican-controlled Senate Intelligence Committee, which subpoenaed the first son.

"Pretty low," Bash replied. "I think he’ll resist or take the Fifth [Amendment].

Bash said this "is a moment of truth for Mitch McConnell, it's a moment of truth for Senate Republicans."

He also suggested that it was likely Trump, Jr. took the Fifth Amendment before Congress and special counsel Robert Mueller's grand jury.

"He’s clamming up," Bash said. "He clearly has something big to hide."

Watch: