Sen. John Cornyn, R-Texas, criticized President Obama and Attorney General Eric Holder on Tuesday for trying to block a book by Fast and Furious operation whistleblower John Dodson.

“After years of stonewalling, conflicting statements and politically timed redactions, it's clear that when it comes to Operation Fast and Furious, the administration is using every tool in the shed to keep something from the American people,” Cornyn said to Breitbart News. “The president and Eric Holder have kept thousands of files locked up that could provide answers and closure to the families of the victims of Fast and Furious."

Cornyn, a frequent critic of the botched operation, called for Holder’s resignation in June 2012.

"The main question that remains is: What are President Obama and Eric Holder hiding?” he asked.