Trump-Russia special counsel Robert Mueller completed his investigation without ever interviewing President Trump. The two sides wrangled over the issue for much of the Mueller investigation before Trump finally agreed to answer questions in writing. Now, in a new podcast interview, a former lawyer for the president, John Dowd, said the wrangling became so contentious that he threatened Mueller with "war" if the special counsel subpoenaed the president.

Dowd, who was Trump's lawyer from June 2017 to March 2018, said Mueller was hampered by two daunting problems. The first was that Mueller could not establish that a crime had occurred — that there had been conspiracy or coordination between the Trump campaign and Russia to fix the 2016 election. Indeed, the Mueller report, as quoted in Attorney General William Barr's summary of its findings, said "the investigation did not establish that members of the Trump campaign conspired or coordinated with the Russian government in its election interference activities" and "the evidence does not establish that the President was involved in an underlying crime related to Russian election interference."

Mueller's second problem, as Dowd and the Trump team saw it, was that precedent from a Clinton-era independent counsel investigation, the Mike Espy case, held that to overcome a presidential claim of privilege, a prosecutor had to show that the president's testimony would provide evidence that was directly relevant to a criminal matter, and that that evidence was not available from any other source. Dowd argued that the White House had cooperated so extensively with Mueller, had provided him so much material that helped explain the president's actions, including contemporaneous accounts of what Trump said in private conversations, that Mueller could not effectively claim that he had no other source of information.

Mueller and the president's team went back and forth on the question of a presidential interview for quite a while. "[Mueller] said, 'Well, John, I need to know what was in the president's head,'" Dowd recalled. "I said you already do, you know in real time."

The conflict dominated a difficult March 5, 2018, meeting. "I asked, what's the president's status?" Dowd said. "[Mueller said] he's a witness-slash-subject. And I said, you mean he has no exposure? He said that's right. So I knew then for sure, by inference, that [Mueller] had nothing to proceed on in the collusion and conspiracy area."

Still, Mueller said he needed to interview Trump, and that he might subpoena the president.

"He dropped that on the table, and I reacted very strongly," Dowd recalled. "I said go ahead, you're threatening this president with a subpoena. It's doubtful whether the [Justice Department] Office of Legal Counsel would have approved such a thing. ... But beside that, I said, well go ahead. I want to hear what you tell the court is your basis to do it when you don't have a crime, you've just told me [Trump] doesn't have any exposure, so what are you going to tell a U.S. district judge? Because we're going to move to quash this thing. And Jay Sekulow and his team were ready to do it ... We're ready to do it if you want to do it."

"Then he backed off, he said don't get upset," Dowd continued.

"I said, look, what basis do you have to do it? We're not afraid of a grand jury subpoena. You want to do it, you've got yourself a war and you're going to lose it. There's no way [Mueller] could win that. I think he concluded that, even with all the firepower he had on his side, I think they knew they couldn't do it. I think they thought they might scare us into it, but we were not going to go there."

The subpoena never came.

Turning to today's situation, Dowd said he was favorably impressed with Barr's summary of Mueller's key findings. But he felt Barr should have included a description of the Trump White House's cooperation with Mueller. As an example, Dowd pointed to notes taken by Annie Donaldson, a top aide to Don McGahn, then the White House counsel. Donaldson was present at critical meetings with the president and McGahn, and also Reince Priebus, then the White House chief of staff. She took detailed notes of the meetings, including what the president said. If she was not in the meeting, McGahn would go back to his office and dictate to Donaldson what had taken place.

All those notes were turned over to Mueller. "I challenge anyone to find a president that was so fully cooperative or transparent, and I must say particularly the intimate notes of his counsel and other senior staff that we produced," Dowd said. "Annie Donaldson's notes will take you 15 hours to read through them. They are the real-time comments and thoughts of the president in conference with Don McGahn and other lawyers at various times, and chief of staff Priebus, and other people. It was remarkable that that material was produced."

Dowd was well-known as an advocate of cooperation with the Mueller probe, believing it would help Mueller finish his job quickly. In that, he was disappointed. Dowd hoped Mueller would be done by the end of 2017 — "By early December, he had exhausted all of the evidence and the witnesses" — but the investigation dragged on until March 2019. Still, Dowd's cooperation policy yielded other benefits. Most significantly, it was a powerful argument against the accusation that Trump obstructed justice. "How could you possibly think this guy obstructed when he was so cooperative?" Dowd asked.

Yet Mueller appears to have left the obstruction question open. The Mueller report, as quoted by Barr, said the obstruction investigation raised "difficult issues," adding, "While this report does not conclude that the President committed a crime, it also does not exonerate him." Dowd said he was perplexed by Mueller's decision not to make a decision.

The bottom line is that Dowd is happy the investigation is over but unhappy it ever started. Despite the media frenzy, he said, the evidence showed there was simply nothing to the theory of Trump-Russia collusion. And yet the special counsel investigation went on for 674 days. Even now, the accusations of collusion and obstruction are still flying. "It's probably the biggest fraud ever committed against the people of the United States," said Dowd.