Marilyn Monroe.

When Jacqueline Kennedy spoke in public, her voice carefully modulated, sometimes barely above a whisper, she sounded more than a little bit like Marilyn Monroe, of all people. Check out the YouTube video of Mrs. Kennedy’s famous White House tour, close your eyes, and tell me I’m wrong.

Natalie Portman does an uncanny job of capturing Jackie Kennedy’s cadence, as well as her walk and her mannerisms, in “Jackie.” Ms. Portman is sure to be nominated for an Oscar for her performance, and deservedly so — even though there were some moments when the dialogue and the intrusive score and the overt symbolism came dangerously close to camp.

Pablo Larrain’s “Jackie” is a morbid, uneven, sometimes elegant, sometimes insightful, occasionally Lifetime movie-ish examination of the immediate aftermath of the assassination of JFK, as told through the lens of the First Lady who refused to change out of the blood-stained pink Chanel suit she was wearing on Nov. 22, 1963, famously saying, “Let them see what they’ve done.”

“Jackie” is not about JFK’s presidency, or any conspiracy theories about his assassination. The president, as well as LBJ and Lady Bird Johnson, are peripheral players in this telling of one of the most filmed and interpreted historical acts in cinema history.

This is all about how the 34-year-old First Lady became a widow in one horrible instant and had to deal with the horror of holding her husband’s brains in her hands; the grief of losing her husband; the task of telling her two young children Daddy was up in heaven and was never coming home; the planning of the funeral, and oh yes, figuring out what in the world she was going to do with her life now that she and the children would be moving out of the White House.

Director Larrain and screenwriter Noah Oppenheim rely on the time-honored technique of framing the story via an interview conducted by a fictitious journalist. In this case the journalist (Billy Crudup) is a character clearly inspired by Theodore H. White, whose extensive interview with Mrs. Kennedy one week after the assassination resulted in a famous Life magazine article that gave great credence to the whole Kennedy/Camelot mythmaking machinery.

The journalist is cynical and condescending, occasionally offering his own opinion when he should be LISTENING. Jackie keeps reminding him she will have editorial control over the interview. At times she pours out her heart and goes into graphic detail about the assassination — only to quickly compose herself and tell the journalists he won’t be able to print any of that.

The interview interludes are the least effective segments in the film. Far more fascinating are the time-jumping flashbacks, whether Larrain is expertly re-creating the aforementioned 1962 tour of the White House, capturing the chaos aboard Air Force One when LBJ was sworn in and various aides immediately begin referring to him as “Mr. President” as a dazed Jackie babbles on about getting Irish bagpipers to play at the funeral procession or focusing on Jackie’s abject grief when she finally takes off the pink suit, rolls off the blood-speckled nylons, rinses off the blood in the shower and crawls into a luxurious bed, all alone.

Peter Sarsgaard would seem to be an unorthodox casting choice to play Bobby Kennedy, but he’s outstanding as the president’s younger brother, who is fiercely protective of Jackie and combative with anyone that messes with her vision of JFK’s funeral and his final resting place. Greta Gerwig is excellent as Nancy Tuckerman, the social secretary at the White House and, at least in this telling of the tale, Jackie’s closest friend.

Portman is doing an impersonation, but it’s not a superficial one. She captures the almost brittle beauty of Jackie — but she also does a fine job of conveying Jackie’s underestimated toughness, and yes, the calculated efforts just after the assassination to make sure her husband’s legacy was perhaps even greater than his actual accomplishments in office.

The attention to detail to the sets, the fashion, the feel of the early 1960s, is spot on. “Jackie” is not a great film, but it’s a great-LOOKING film.

Nor is subtlety the order of the day. Jackie throws down drinks and turns the volume up on the Broadway recording of “Camelot.” Lady Bird Johnson starts planning a makeover of the White House before Jackie and the kids can even move out.

Jackie regards herself in the mirror and in reflections many, many times. Jackie stomps around a rain-soaked Arlington National Cemetery in heels, struggling to stay on her feet while scouting out the perfect location for her husband’s grave.

But Portman’s performance carries the day.

★★★

Fox Searchlight presents a film directed by Pablo Larraín and written by Noah Oppenheim. Rated R (for brief strong violence and some language). Running time: 92 minutes. Opens Friday at local theaters.