WASHINGTON (Reuters) - Many left-leaning Americans regarded Special Counsel Robert Mueller as a paragon of courage and toughness, an unflinching prosecutor who would stop at nothing to ensure justice was served to President Donald Trump.

FILE PHOTO: Robert Mueller, as FBI director, testifies before a Senate Intelligence Committee hearing on Capitol Hill in Washington March 12, 2013. REUTERS/Kevin Lamarque/File Photo/File Photo

A decorated Marine platoon commander in the Vietnam War, Mueller burnished his credentials by bringing charges against former Trump aides even while under attack from the White House.

Now, after reading the 448-page report on his investigation into Russian interference in the 2016 election, some are asking whether the former FBI director was tough enough.

In interviews with more than 20 Mueller supporters, former prosecutors and legal experts, Reuters found that criticism has centered on two decisions: declining to make a call on whether Trump committed a crime by obstructing justice, which allowed Attorney General William Barr to intercede in Trump’s favor, and failing to compel the president to answer questions under oath.

“The most critical thing is he didn’t insist on an interview with President Trump,” said Melanie Sloan, a senior adviser with the American Oversight, an ethics watchdog which has filed more than 70 public-records lawsuits against the administration since Trump was inaugurated in January 2017.

Trump claimed victory after Barr said last month that Mueller had not established a conspiracy between Trump’s campaign and Russia, and went further by declaring there was no prosecutable crime on obstruction.

Supporters said Mueller’s full report released on Thursday was actually more damaging than Barr’s summary led them to believe, documenting a pattern of lies by Trump and laying the foundation for Congress to take up a possible obstruction case.

And while Mueller adhered to Justice Department policy not to indict a sitting president, he specifically said his investigation “does not exonerate him” and noted that a president could face criminal liability after leaving office.

“What he gave us is a blueprint for a future prosecutor to go to a grand jury and indict,” said Jennifer Taub, a professor at Vermont Law School, though she pointed out that such a move could be subject to a pardon. “I think he did an excellent job.”

A spokesman for Mueller declined to comment.

A LET DOWN?

Still, many Mueller devotees who were sure Mueller’s probe would end Trump’s presidency made it clear they felt let down.

“There was a little flinching at the end of the day,” David Brock, founder of Media Matters for America, a media watchdog known for its criticism of conservative news sites.

In particular, a face-to-face interview could have yielded new evidence on intent and caught Trump lying, some legal experts said.

“If Trump lies and those lies were exposed in the report, I think it would have been much harder for Barr to exonerate him,” said Lawrence Robbins, a Washington-based trial and appellate litigator.

In the report Mueller explained that he was concerned about a lengthy court battle if he subpoenaed Trump, who had declined to be interviewed voluntarily. Mueller also said he had secured substantial information from other sources.

But if time was such a big consideration, he could have sought a subpoena early on, said Nelson Cunningham, a White House lawyer under President Bill Clinton.

In the Whitewater investigation in the 1990s, independent counsel Kenneth Starr obtained a subpoena to compel Bill Clinton’s grand jury testimony about his relationship with intern Monica Lewinsky.

Clinton agreed to testify and was later accused of perjury and obstruction. He was impeached by the House of Representatives but acquitted in the Senate.

“Trump is the central figure in this entire matter and not to have sought his testimony like Starr did in 1998 - it just seems to leave a giant hole in Mueller’s two years of work,” Cunningham said.

Mueller’s failure to declare whether Trump committed the crime of obstructing justice is another key point of contention.

Mueller said in the report that his stance was warranted because Trump would not have the normal recourse of a speedy and public trial to clear his name.

“I think that is why he was appointed – to see if there were crimes – and I think that is a major inexplicable failure,” said Matthew Jacobs, a former federal prosecutor who is now a defense lawyer based in San Francisco.

By declining to make that call, Mueller effectively handed the decision to Barr despite knowing that the future attorney general had argued against the legitimacy of Mueller’s obstruction case in a memo to the Justice Department.

Mueller must have known what the consequences of his inaction would be, said Jimmy Gurule, a former assistant attorney general who served under Barr in the early 1990s.

“Now we are in this legal black hole,” said Gurule, now a law professor at the University of Notre Dame.