Deputy Attorney General Rod Rosenstein. AP Photo/Patrick Semansky While President Donald Trump's decision to fire the FBI director, James Comey, came as a shock for many, reports now say even a person said to be an architect of the dismissal was surprised with the way the firing was presented to the news media.

Deputy Attorney General Rod Rosenstein, who had written a three-page memorandum detailing the reasons behind his recommendation for Comey's dismissal, was painted by the White House as the main arbiter of the decision.

Trump had said he acted based on the recommendations of Rosenstein and Attorney General Jeff Sessions.

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

The Justice Department denied on Thursday morning that Rosenstein had threatened to resign. But Rosenstein was angry that the White House had carried out Comey's termination the way they did, according to CNN.

As many have noted, Rosenstein used his letter to outline his concerns with Comey's leadership, but he did not recommend that Comey be fired.

The Post reported Wednesday that it was actually Trump who spearheaded Comey's firing. According to multiple news reports Wednesday night, Trump had grown increasingly angry and frustrated over Comey's handling of the investigation into whether the Trump campaign colluded with Russian officials to meddle in the 2016 election. The New York Times reported that Trump was also bothered by his inability to gain assurances of loyalty from Comey.

"He wasn't doing a good job," Trump said Wednesday in his first public comments about Comey's removal. "Very simple. He wasn’t doing a good job."

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

But sources cited by CNN said Rosenstein's purported 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."

Natasha Bertrand contributed to this report.