(CNN) Senate Judiciary Chairman Charles Grassley, an Iowa Republican, has taken interest in why an early draft of a memo by then-FBI Director James Comey described the behavior of Hillary Clinton as "grossly negligent" for her handling of classified information, though Comey in his July 5, 2016 public statement didn't use that term.
A source familiar with the FBI decision tells CNN that Comey and his FBI colleagues were "playing with the language throughout" the process, but consistently held the belief that they needed to condemn Clinton's handling of classified information while asserting they would not bring charges.
Instead, Comey ended up criticizing Clinton's conduct as "extremely careless," but said no reasonable prosecutor would pursue charges based on the evidence.
"Although we did not find clear evidence that Secretary Clinton or her colleagues intended to violate laws governing the handling of classified information, there is evidence that they were extremely careless in their handling of very sensitive, highly classified information," Comey said in July.
"Grossly negligent," the language dropped from the draft, is a term that carries with it legal ramifications. "Extremely careless," the term Comey ended up using, does not. So why the change?
Grassley wrote a letter to FBI Director Christopher Wray demanding an answer.
"Although Director Comey's original version of his statement acknowledged that Secretary Clinton had violated the statute prohibiting gross negligence in the handling of classified information, he nonetheless exonerated her in that early, May 2nd draft statement anyway, arguing that this part of the statute should not be enforced," Grassley wrote.
A source familiar with the decision-making process at the FBI at the time tells CNN that "the Bureau and Jim were trying to see what a statement of declamation might look like -- and they were playing with the language throughout. The one thing that's a constant is that they thought what they had seen so far, subject to change, was that charges would not be appropriate but that the conduct was worthy of criticism. It was a matter of how to explain both."
"They wanted to get a sense of what this statement might look like," the source said. "They hadn't stopped investigating and they were continuing to seek access to all sorts of things from Hillary that she was fighting to have to turn over. But they also wanted internally to discuss what an end game might look like."
Throughout this end game, the source said, Comey thought that while the while there was evidence of violations, no reasonable prosecutor would proceed. Which is what he stated on July 5, 016: "Although there is evidence of potential violations of the statutes regarding the handling of classified information, our judgment is that no reasonable prosecutor would bring such a case."
Comey later explained his reasoning during marathon congressional testimony on July 7, 2016. At that point he did use the word "negligent," but not "grossly negligent."
"I think she was extremely careless. I think she was negligent -- that I could establish," Comey told the House Oversight and Government Reform panel. "What we can't establish is that she acted with the necessary criminal intent."
Correction: Due to an editing error, this post initially quoted James Comey as calling Hillary Clinton both "extremely reckless" and "extremely careless." He said she was "extremely careless."