Comey furious at lack of respect White House showed, sources say

— -- Former FBI Director James Comey was furious at the lack of respect the White House showed him in the way he was fired, sources have told ABC News.

Associates say he is simmering at some of the comments directed at him by White House staffers, who have used words like "atrocities" to describe his actions as director.

One person close to the former director said that President Trump calling Comey a "showboat" and suggesting he is not "competent" has required Comey to show considerable restraint.

"Look, he's a showboat. He's a grandstander," Trump said about Comey in an interview with NBC's Lester Holt on Thursday. "The FBI has been in turmoil. You know that. I know that. Everybody knows that."

A source said they expect that at some point Comey will respond to Trump -- but it is uncertain when that would be. For now, Comey has taken a few days to gather himself, particularly given how caught off guard he was by the timing of the firing.

The only public statement from Comey since his dismissal came in the form of a letter he delivered to former FBI colleagues on Wednesday.

"I have long believed that a President can fire an FBI Director for any reason, or for no reason at all," he wrote. "I'm not going to spend time on the decision or the way it was executed. I hope you won't either. It is done, and I will be fine, although I will miss you and the mission deeply."

To announce Comey's firing, Trump had a dismissal letter hand delivered to the FBI's building in Washington, although the former FBI Director learned of his firing from an aide as Comey was away in California on a recruiting trip for the bureau at the time.

Sources say that inside the FBI, many agents feel Comey has been treated shabbily. While there are those who disagreed with some of his tactics, he was nonetheless broadly popular in the bureau and respected.

While the sources added that this has been a tumultuous week, with many employees of the bureau thrown off balance, there is also a degree of resolve settling in.

In the meantime, some individuals associated with the bureau have publicly rallied to protect Comey's name.

During a hearing on Thursday, acting FBI Director Andrew McCabe told the Senate Intelligence Committee that Comey was held in high regard in the organization, despite White House deputy press secretary Sarah Huckabee Sanders saying during a press briefing on Wednesday that "the rank and file of the FBI had lost confidence in their director."

"I can tell you also that Director Comey enjoyed broad support within the FBI and still does to this day," McCabe said when asked about Comey.

McCabe's assessment about Comey's level of support was subsequently backed up by the FBI Agents Association.

"Director Comey enjoyed broad support and respect within the Bureau," Thomas F. O'Connor, the association's president, said in a statement released Thursday. "He was a consistent and strong advocate for Agents. As we move forward, Agents continue to do our work with the same level of professionalism and commitment that the American people expect and deserve."