Over the next few months, as Republican and Democratic candidates vie to be their party’s nominee and then face off in November’s presidential election, menswear aficionados will be able to judge the candidates’ sartorial prowess over a vast array of dress codes, from business-formal to blue-collar festive. Here at MR PORTER, we want to make a bipartisan effort to elevate the style quotient of the current candidates (and help the rest of us, who may find ourselves wondering what to wear on a visit to a car factory, hog roast or town hall). So we’ve borrowed a few moves from Messrs John F Kennedy and Ronald Reagan to put together this foolproof guide to POTUS style.

Like many professionals who spend their working week in a suit, casual dressing can be a minefield for presidential candidates. While the desired effect of jumpers is meant to vibe relatable family man, the current field looks more tech mogul at a Ted talk. Messrs Marco Rubio, senator for Florida, John Kasich, governor of Ohio, and Jeb Bush, the dynasty standard-bearer, have all succumbed to zipped-neckitis. Clearly, the look is viewed as too democratic by Republican voters and has hindered these men in their efforts to derail the defiantly un-woollied Mr Donald Trump as he rolls towards the nomination. The height of knitwear power politics, however, belongs to President Jimmy Carter who, in 1977, went on national television and boldly turned down the White House thermostat to 18°C (65°F). He donned a chunky (and eerily on-trend) shawl-collared cardigan and advised his fellow Americans to conserve heating oil by layering up (again, eerily on-trend). The sweater softened his shirt and tie (take note, business-casual officer dwellers) and his trustworthiness ratings spiked.

The photo opportunity on an assembly line or other blue-collar haunt has tripped up many a candidate. The box-fresh Red Wing boots and acrylic law-enforcement windcheater can make a candidate look like he’s auditioning for Village People. The best candidates stay suited and unbooted when operating heavy machinery. Sitting on a tractor has long been a way for presidents to send out a vibe of corn-belt authenticity. President Warren Harding, one of the most corrupt and scandal-ridden chief executives the US has known, did not attempt to play at dressing up when he rode this tractor in 1923. We would advise the current field to stick to a blue blazer and chinos and accessorise with a gimme cap that bears the plant or trade union’s logo.

When Senator John F Kennedy debated with former Vice President Richard Nixon in Chicago on 26 September 1960, it was the first time a presidential debate had been televised. Mr Kennedy was made for the medium and brought his grooming A game, including a natural base tan (take note, Mr Trump). Mr Nixon did not shave and had five o’clock shadow. He was also sallow of complexion because he was recovering from a knee injury. When the two entered the CBS television studio, Mr Kennedy publicly declined make-up. Mr Nixon followed suit, not wanting to appear soft. Backstage, however, Mr Kennedy had a professional make-up artist burnish his mahogany-coloured skin. Meanwhile, Mr Nixon panicked and had an aide run to a local drugstore and buy him some five o’clock shadow concealer. The TV audience succumbed to Mr Kennedy’s youthful sheen, while voters who listened on the radio preferred Mr Nixon, oblivious to his murky maquillage.

The job’s in the bag and it’s time to pull out all the stops. Statesmanlike overcoat, cashmere scarf, bells, whistles. Historically, up to and including Mr Nixon, the president wore morning dress for the inauguration ceremony, but it was downgraded to a suit and tie combo by Mr George HW Bush in 1989. There are two ways to play it. Wasps, the sort of people who believe machismo equals swimming in frigid New England waters, try to brave the weather in just a suit. For others, the topcoat and scarf are key to projecting commander-in-chief gravitas. Mr William Howard Taft, who was the US’s most well-marbled president, weighing in at 150kg (330lb), was fond of a double-breasted topcoat with fur cuffs and collars. Come January 2017, if the new POTUS wants to look current, we’d recommend this Berluti overcoat and Begg & Co scarf, because cashmere is something we can always get behind.

When it comes to pulling off field clothing, Republicans have a better track record than Democrats. This could be because The Party of Lincoln lives to chop government spending and dismember the welfare state (one of President Abraham Lincoln’s nicknames was Rail Splitter). Particularly adept in this respect, Mr Ronald Reagan even looked good in double denim when he was clearing brush at Rancho del Cielo, his holiday home in the Santa Ynez Mountains, northwest of Santa Barbara. The key here is pairing workwear with actual work. The notoriously baggy, dad-style “Obama jeans” that some older men sport at the weekends tell quite a different, less hands-on story.