The most iconic piece of first lady clothing in all of fashion history is no pretty sight. Too upsetting for public display, it is sealed in a climate-controlled vault of the National Archives near Washington DC, where it will be kept hidden until 2103, a purdah imposed, when it arrived with an unsigned note on the stationery of Jackie Kennedy’s mother, Janet Auchincloss, which read simply: “Jackie’s suit and bag – worn November 22, 1963.”

The pink suit that the first lady wore that fateful day in Dallas is still stained with the blood of a president, the dying husband she cradled in her lap in an open-top car, an image of lurid public horror. Famously, Jackie Kennedy refused to change into a new outfit in the aftermath of the assassination. “Let them see what they have done,” she is reported to have said, before exiting the plane in Washington hand-in-hand with her brother-in-law. Afterward, the suit, along with her navy shoes and bloodied stockings were folded and stored without cleaning. In this debased, violated state, the suit is the most visceral of relics.

The world awaits an inauguration on 20 January 2017 that feels more like a moment of political disruption than the smooth transfer of power. An inauguration ceremony is designed to oil the wheels of change, yet this one feels more like a revolution. The president-elect is fresh from a bruising, lurid run-in with the political establishment. In the absence of A-list talent, police marching bands are expected to be high profile, which will lend the event a militaristic tone. And rebellion is already planned, in the form of the Women’s March on Washington on Saturday 21 January 2017.

Peter Sarsgaard as Bobby Kennedy and Natalie Portman in the title role in Jackie.

Photograph: Allstar/Fox Searchlight Pictures

On the day the United States welcomes a new first lady – with Trumpian unpredictability it is as yet unclear if this is to be Melania or Ivanka or some combination of the two – the spirit of the first among first ladies, Jackie Kennedy, arrives on our cinema screens in the form of Natalie Portman in Jackie, a film whose central action takes place with the protagonist wearing a bloodied pink skirt suit. The suit is a reminder that first lady fashion, which is under a fierce spotlight right now with the departure of Michelle Obama and the arrival of Melania and Ivanka Trump, can represent the dark side of politics as well as the sunlit uplands of Camelot, or the progressive dream of the Obama White House.

The Life magazine special issue of commemoration for JFK opened with a full-page photo of the couple arriving at the Dallas airfield, with the saturated pink of Jackie’s suit perfectly offset by the blue Texan sky. The art historian David Lubin has described how “the Kennedys look tall and vibrant … they seem within our reach, giants among us,” and noted that the spray of red roses that Jackie clutches foreshadow the blood that will stain the suit a few hours later.

The pink suit, which returns to public life with Portman’s film, is doubly powerful because it represents both the image that Kennedy painstakingly constructed, and the shock of how her life, and political history, was derailed by violence. We are just now beginning to understand Kennedy as a woman at least a generation ahead of her time, in her innate understanding of visual messaging. In an essay that won her first prize in a prestigious Vogue writing competition as a student, she speculated about becoming “a sort of Overall Art Director of the Twentieth Century”. In the film Jackie, we see her as the chain-smoker she was, an unladylike habit she successfully kept entirely hidden from the public. The colour choice of the pink suit – a favourite, which she had worn during a visit to London and to meet the Algerian prime minister – seems calibrated to amplify her feminine appeal, its shade drugstore-lipstick bright against her naturally cool colouring. The silhouette of the suit, like that of the bateau-necked red suit, which also stars in the Portman film, stands apart from her own body. The raised neckline is stiff as battlements, her own shape revealed only by abbreviated sleeves, which suggest, by those tiny wrists, the fragile body underneath. “Rather than follow the contours of her body, her formal clothes sit almost in conflict with them,” writes Stella Bruzzi in her essay on the pink suit.

The suit is often said to be Chanel, but the truth is that it was an authorised copy of a Chanel design, signed off in Paris but made for her at the Park Avenue salon of Chez Ninon. This was a strategy employed by Jackie Kennedy to circumvent public disapproval of her disloyal taste for European style, without compromising her own wardrobe.

Gigi Hadid on the Bottega Veneta catwalk, SS17, Milan fashion week, September 2016. Photograph: Maestri/WWD/Rex/Shutterstock

By the happenstance of taking place outdoors in Washington in January, inaugurations can look sombre. Almost funereal, in fact. Eight years ago, Michelle Obama trumped this by virtue of her and her daughters’ brightly coloured coats, scarves and gloves, which brought festive cheer into bleak midwinter. Pink is, by coincidence, a headline trend to have emerged from the most recent catwalk shows. On the Bottega Veneta catwalk, current American sweetheart Gigi Hadid wore a pink two-piece with a diagonal row of outsize gold buttons, which had a touch of Kennedy’s formal glamour. (The bottom half was, for 2017, loose trousers rolled at the ankle, instead of a knee-length skirt.) Some participants in Saturday’s march plan to wear pink “pussy hats” – knitted with pointed cat ears, a symbol of female defiance of Trump. Bruzzi quotes Norman Mailer, who thought JFK’s brilliance was to create a dazzling empty slate, on to which we projected what we wanted to see. JFK’s “magnetism is that he offers us a mirror of ourselves”, Mailer wrote. The pink suit will not be seen in our lifetimes. But its status as first among first lady images is alive and kicking.