“Mitt,” the new documentary about Mitt Romney’s presidential campaign, will not fundamentally change people’s perceptions of the 2012 Republican nominee. Lengthy campaigns reveal character and personality and harden voters’ impressions of all the candidates. Romney’s image is well-fixed.

But the behind-the-scenes documentary, which had its first public showing Friday night in Salt Lake City as part of the Sundance Film Festival and will be available on Netflix on Friday, is nonetheless quite revealing. The movie fills out a portrait of Romney as a politician of self doubt, self awareness and, yes, self confidence.

The compelling film is the work of Greg Whiteley, who won Mitt and Ann Romney’s permission to trail them with a camera through two races for the White House. Inside stories of campaigns are usually told through the eyes and commentary of a candidate’s advisers, mostly after the fact. Whiteley’s contribution is to take us even further in, to the candidate and his family rather than just his staff, and to do so in real time.

Romney’s doubts about his capabilities as a candidate are seen at various points throughout the movie. The Washington Examiner’s Byron York highlighted them in an article published over the weekend.

Shortly before the first candidate debate, in October 2012, Romney acknowledges being intimidated by the prospect of going head to head with President Obama. It’s seemingly left to Ann Romney to put steel in his spine.

The trailer for the Netflix documentary, "MITT." (Courtesy Netflix)

“You should not be intimated by him, I am not kidding, Mitt,” she says. Romney responds, “He’s a very good debater. He’s a lot better than the other guys. I’ve watched his tapes. He does a very nice job.”

Is Romney wracked by doubt or realistic in knowing that the president is a better politician than any of the Republicans who challenged him for the nomination in 2012? When Texas Gov. Rick Perry said it was the “weakest field ever,” he was not far off, and Romney knows it.

Whatever flutters Romney felt heading into that debate, however, must have quickly melted away onstage in Denver. He was crisp, aggressive and appealing enough to make Democrats worry. It was Obama who seemed, if not intimidated, unsteady in the hand-to-hand combat during the exchange.

That Romney harbored doubts about his candidacy was known before. An early scene in “Mitt” shows the Romney family in Utah in December 2006, discussing the pros and cons of a presidential bid. What the scene does not show is that, ultimately, he and his family unanimously agreed that he should run in 2008.

Whiteley apparently was not in Hawaii in December 2010, when the Romney family had a similar discussion. This time, when the roll was called, 10 family members voted against a second campaign, among them the prospective candidate. Only Ann Romney and their eldest son, Tagg, voted in the affirmative.

Romney doubted whether he was the strongest Republican to challenge Obama, he later said. If someone such as Jeb Bush had run, he might not have. He had doubts about whether the Republican Party would accept him. As he put it the day after he lost to Obama, speaking to his campaign staff, he was a Northerner, a Mormon and a rich guy in a party that was Southern, evangelical and populist.

Take some of these expressed doubts with a smidgen of skepticism. It has been said that in conversations with business partners or political advisers, Romney often expressed pessimism or outlined what could go wrong. Add to that the natural self-doubt that affects practically all people at points in their lives. Most everything else about Romney’s background suggests that he is highly competitive and driven to succeed at whatever he tries.

He may have been a candidate who too often reinforced negative caricatures of himself, but he also displayed signs of self awareness. One comes relatively soon in the film, during his first campaign. It is early in 2008, and he’s down and almost out of the running.

His brother, Scott, says the race is not over. Romney isn’t listening. He knows that John McCain has outdone him and will be the 2008 nominee. “I don’t even want to go to events. . . . I can’t fake it,” he says. How human.

He laments that Republicans have “done the same thing we’ve always done. We get the old guy who’s in line.” One of his sons pipes up, “If that’s the case, you’re the next guy in line.”

Romney remarks ruefully that he has spent part of his personal fortune to build a political brand that, in the end, helped sink his candidacy. “When this is over,” he says, “people will know what I stand for — the flipping Mormon.”

His self awareness is also on display after his second debate against Obama. He had flubbed an exchange about Benghazi that night. Obama accurately claimed he had used the words “acts of terror” the day after the raids in Libya that killed four Americans. Romney challenged him. Candy Crowley of CNN, the moderator, sided with the president. Romney was caught flat-footed.

The full story of what Obama said about the attacks is more complex. Although he had used “acts of terror” in a Rose Garden address, in the days after, he resisted labeling them as terrorist attacks. But Romney, normally on top of his brief in the debates with a full knowledge of his opponents’ statements, was not sharp enough at that moment to point out the difference. He was left to look in the wrong.

After the debate, Romney’s family and advisers try to tell him that he had done well in the debate, that there were no winners that night. Romney isn’t buying it. Instant polls show a narrow Obama victory. Politically, it was a good night for the president and a setback for the challenger. Romney makes clear that he knows the score.

The confident Romney emerges in other, perhaps misplaced, ways. He was confident enough on Election Day 2012 that he had written most of a victory speech. He had not written a concession speech. In his hotel suite in Boston, when it’s clear that he has lost, he asks what he should say to the American public.

Chief strategist Stuart Stevens suggests something soothing. Romney dismisses the advice. “Yeah, okay. I don’t think this is a time for soothing and everything’s fine,” he says. “This is a time for, ‘This is really serious, guys. This is really serious.’ To get up and soothe is not my inclination.”

He was ready to concede the presidency but not the argument — confident in his convictions about what the country needed. “I believe that we’re following the path of every other great nation,” he says, “which is we’re following greater government, money, tax the rich people, promise more stuff to everybody, borrow until you go over a cliff. I think we have a very high risk of reaching the tipping point sometime in the next five years.”

Filmmaker Whiteley, with the consent of Mitt and Ann Romney, has done a great service by revealing private moments to public view and reminding everyone that behind the carefully calculated facades of presidential candidates are multidimensional humans.