President Donald Trump. Michael B. Thomas/Getty Images White House special counsel Ty Cobb, who was appointed to represent President Donald Trump in the Russia investigation, on Saturday issued his lengthiest statement yet about a letter the president wrote in early May laying out his reasons for firing former FBI Director James Comey.

Trump reportedly listed Comey's refusal to confirm publicly that he was not personally under FBI investigation as one reason for his dismissal. White House counsel Don McGahn ultimately blocked him from sending the letter, according to reports last week in The New York Times and Washington Post. The letter is now being examined by FBI special counsel Robert Mueller.

In an email to Business Insider on Saturday night, Cobb took direct issue with a story published on Saturday afternoon outlining how the advice McGahn gave to Trump about the letter could prove pivotal in the obstruction of justice case that Mueller has reportedly been building against the president.

Cobb disputed the characterization of the president's letter as incriminating — and therefore blocked by McGahn — and called reporting to that effect "exaggerated and/or fictionalized."

"The 'letter', which, in fact, contained detailed views which the President presented for comments from senior staff, was the President's creation, is wholly exonerating and has been with the SC [Special Counsel] for sometime," Cobb wrote. "Its existence was long known to them and to the Department of Justice which has had a copy since the day it was first discussed within the White House."

He continued:

"The White House willingly authorized the physical delivery of the 'letter' to the SC. Rabid though the press may be on the issue, the original memorandum of the President's thoughts in letter form, the related Department of Justice analysis (which was first initiated before the President independently memorialized his thoughts), the subsequent conclusions of the Department of Justice, and the ultimate summary of each in the final termination letter are quite consistent and focus on the former Director's usurpation of powers and other erratic and inexplicable conduct."

The White House maintained in the days after Comey was fired that his dismissal had been based on recommendations from Attorney General Jeff Sessions and Deputy Attorney General Rod Rosenstein.

But Sessions and Rosenstein reportedly wrote the memos outlining their reasons for firing Comey after Trump presented them with a copy of the termination letter he wrote following Comey's testimony before the Senate Judiciary Committee on May 3.

Asked if the DOJ agreed with the president that Comey's behavior was "erratic," Cobb responded, "Clearly, as the long public RR memo explains and as Comey's early and subsequent testimony have caused commentators to make forceful allegations of perjury and the newly disclosed related testimony of senior FBI officials make clear."

Cobb did not provide examples of perjury allegations, but Trump has maintained that Comey lied when he told the Senate Intelligence Committee on June 8 that the president had asked him to drop the investigation into former national security adviser Michael Flynn.

Comey documented the February 14 meeting in notes that he gave to a friend to pass along to a New York Times reporter after he was fired. Those notes are now in Mueller's possession.

Former FBI Director James Comey Drew Angerer/Getty Images

Longtime federal prosecutor Renato Mariotti, who first argued that McGahn's testimony could prove central to Mueller's obstruction case, told Business Insider that it is "very hard to believe that Trump's letter, which has been described as a 'rant,' was consistent with a careful analysis by Rod Rosenstein."

Mariotti also noted that Cobb said Trump's letter was "quite" — rather than entirely — consistent with Rosenstein's memo, leaving room for a potential disconnect. Rosenstein's memo also does not mention Russia at all, as Trump's letter reportedly did.

Trump reportedly drafted the letter with Stephen Miller, his policy adviser and an ally of former White House chief strategist Steve Bannon. Miller has emerged as a hardline player in the Trump administration, and has been seen, in some cases, as helping Trump appeal to his more incendiary instincts.

Cobb wrote: "There was broad support and little IF ANY objection within the White House for the action in question which, as your earlier reporting OMITS, was precipitated by and immediately on the heels of Director Comey's Congressional testimony."

Cobb did not explain when asked why, if there was little objection within the White House, the letter was sent to the DOJ rather than Comey himself.

Instead, he asked this reporter via email, "Are you on drugs? Have you read anything else on this???"

As Mariotti noted, Cobb did not rule out that McGahn objected — an objection "that could be very important" to Mueller's obstruction case.

The Wall Street Journal reported last week that Trump's legal team was trying to fend off an obstruction-of-justice charge from Mueller's investigators by arguing that the president has the authority to fire whomever he wants, and that Comey is an unreliable witness.

Cobb also refused to clarify whether the president had already asked the DOJ to look into Comey prior to the May 3 Senate Judiciary Committee hearing, in which Comey testified that the FBI was still investigating whether there was "any coordination" between the Trump campaign and Russian officials during the election.

Responding to questions about his handling of the Hillary Clinton email investigation, Comey testified during that hearing that it made him "mildly nauseous" to think that the FBI "might have had some impact on the election."

Trump was apparently annoyed with Comey for implying that the election was somehow swayed by the director's controversial decision to tell Congress that he was reexamining Clinton's emails 11 days before the election.

Comey had not allowed the White House to review his testimony, which Trump and his aides considered "an act of insubordination," according to Reuters. The Times echoed that report, saying Trump was broadly irked by his inability to gain assurances of loyalty from Comey. He was fired six days later.

Sonam Sheth contributed reporting.