Trump's deputy attorney general reportedly threatened to resign after being painted as the mastermind behind Comey's firing

While President Donald Trump's decision to fire FBI director James Comey came as a shock for many, one of the alleged architects of the dismissal was also reported to have been surprised after the hammer came down.

Deputy Attorney General Rod Rosenstein, who wrote a three-page memorandum detailing the reasons behind his recommendation for Comey's dismissal on Monday, was painted as the main arbiter of the decision.

Trump had asserted that he acted based on Rosenstein's and Attorney General Jeff Sessions' recommendations.

But as Rosenstein was thrust into the spotlight shortly after news of Comey's dismissal broke, he was reported to be taken aback and even threatened to resign, according to an unnamed person close to the White House who was cited by The Washington Post.

According to multiple news reports on Wednesday night, Trump himself had grown increasingly angry and frustrated with Comey over his handling of the Russia investigation. The New York Times reported that Trump was also bothered by his inability to gain assurances of loyalty from the now-former FBI director.

"[Comey] wasn't doing a good job," Trump said on Wednesday. "Very simple. He wasn't doing a good job.

Comey was further criticized by the White House after deputy press secretary Sarah Huckabee Sanders said on Wednesday that he had committed "atrocities" for his handling of Hillary Clinton's email server scandal.

But sources cited by CNN said that Rosenstein's alleged role in Comey's firing seemed out of place.

"It's not consistent that he walked in here with a hit list and James Comey's name was on the top of it," one law enforcement official told the network. "That's inconsistent with who he is and what everyone says. This doesn't pass the smell test of Rod Rosenstein."

It was not immediately clear Wednesday night whether Rosenstein would remain at the Department of Justice.