Ever since John Fetterman, the lieutenant governor of Pennsylvania, won the Democratic nomination for Senate in his state by a landslide, his victory has resonated far beyond local borders. Opinion pieces on the meaning of his triumph have appeared fast and furious, as the success of the burly, self-proclaimed “dude in shorts” has been attributed in part to “vibes” (The Atlantic) and his “unconventional style” (The Philadelphia Inquirer).

“Style” being the operative word.

Put simply, as Mr. Fetterman wrote last year in a Medium post that meaningfully understated the case, he doesn’t look like “a typical politician” — and how he looks has become shorthand for the values and policies he represents. At a time when conventional politicians are increasingly falling out of favor, he presents an apparently viable alternative option.

Now the question is how that will play in the general election and whether, in their quest to succeed, other candidates will follow his lead. If so, it may represent one of the biggest shifts in political communication and subconscious button pushing via dress since female legislators were allowed to go sleeveless in Congress.

After all, not for Mr. Fetterman the bland navy suit, white shirt and red or blue tie that has been de rigueur for the political class for decades. Or not for him most of the time: In 2020 he confirmed via Twitter he had only one suit, a single-breasted dark number, that he wore “for special occasions like Legal Weed, Lurch-themed Halloween pictures, + so they let me in the PA Senate.” (Also, for his official inauguration as lieutenant governor and last month’s primary debate.)

Instead, his usual uniform involves a hoodie and shorts. Often by Carhartt and Dickies, the ur-American work wear brands beloved of blue-collar voters and hipsters. (He called Carhartt and shorts “Western PA business casual” on Twitter.) He wears them in pretty much every context he can.

He wore shorts, for example, to appear on the CBS “Sunday Morning” show. Shorts to many campaign events. And shorts in January to meet with President Biden at the site of a Pittsburgh bridge collapse.

He wore a black Carhartt hoodie to the White House Easter Egg Roll, where he loomed like a Rorschach test amid a sea of pastels, and to fill out his election ballot in his hospital room when he was sidelined with a stroke just before the primary. His official portrait, which hangs in government offices across the state, features him in a black Dickies camp shirt before an American flag.

Although there was a rumor going around, courtesy of GQ, that Mr. Fetterman sometimes wore his favored looks with what the magazine identified as Maison Margiela side-zip boots, Rebecca Katz, a senior adviser to the Fetterman campaign, said that is incorrect; they are actually Florsheim boots. He also has Under Armour and Skechers sneakers, and occasionally wears slides.

Combined with his shaved head, goatee and tattoos (on his left arm, the ZIP code for Braddock, Pa., the town where he was mayor for 15 years; on his right, the dates when citizens of Braddock were killed by gun violence during his terms in office), the effect practically reeks of that word so beloved of the political class, and so rarely associated with them: authenticity.

It’s not that Mr. Fetterman looks particularly à la mode, but that he doesn’t look overly polished, or too fancy, or (yikes) styled. Indeed, he doth protest often that he has “negative fashion sense.” Which, of course, is the point. He looks real, an avatar of the American archetype of the working man who does an honest day’s labor (even though he did go to Harvard for his M.B.A., and his labor is mostly deskbound).

He also presents a visible contrast with Dr. Mehmet Oz, who tends to the Trump uniform of blue suit and bright red tie, and David McCormick (very business casual), one of whom will receive the Republican nomination after the results of that primary recount are in.

As Ms. Katz, the senior adviser, said, “he just wears what feels comfortable.”

At a time when comfort dressing is on the rise, there are worse ways to convince a disparate swath of the electorate that you understand their concerns and will represent them. That electorate may not have the time or inclination to read a lot of policy proposals or platforms or listen to stump speeches, but they know a kindred soul when they see one.

A fact of which Mr. Fetterman is well aware. At least judging from a short video he and the Pennsylvania governor, Tom Wolf, made in 2018 entitled “Gov. Wolf Buys John Fetterman a Tie,” putting his dress sense front and center. Not to mention that Medium post, in which he also admitted, “I even lack the political metaphorical sleeves to roll up — all I ever wear are short-sleeve work shirts because hard work is the only way to build our communities back up.”

An observation that in itself revealed how closely attuned he was to the traditional theater and costume of politics, in case anyone was wondering if all of this happened by coincidence.

After all, the rolling up of the “metaphorical sleeves” is a crucial performative trope in Washington, used, when necessary, to demonstrate serious getting down to business by, as Mr. Fetterman said, most often shucking the jacket and rolling up one’s sleeves to act out the gestures of hard work.

That, or readiness to fight, as in the case of Representative Jim Jordan, Republican of Ohio, who seems to see his jacket as an accessory to be left on the back of his chair when he goes into committee hearings that he expects to be, as he once said, “heated.”

Of course, to take a jacket off, you have to have one on in the first place. And indeed, the capitals of both state and federal government have become the last holdouts in the casualization of office dress, hewing still to the power of the suit, with all the respect for tradition and office that implies.

In choosing a different path, Mr. Fetterman is taking the natural next step in what has been a slow erosion of the political uniform that first became visible during the tieless days of the Obama White House. Though the trend took a big leap backward during the Trump years, it took off again in 2019 with the candidacy of Beto O’Rourke, famous for his sweaty shirt-sleeves, and has been given new life by Senator Kyrsten Sinema, whose willingness to buck all convention in her dress has become intrinsically connected to her own brand of renegade politics.

The effect is unexpected enough to startle anyone out of a political stupor, and serves to make the protagonist in question immediately identifiable and memorable. In a world of white noise and short attention spans, that’s an advantage.

Of course, if Mr. Fetterman wins in November, what happens to his wardrobe next may be an issue. The dress code of the Senate chamber (at least for guests) dictates “business attire,” and male senators are still required to wear coats and ties.

According to Ms. Katz, the candidate will deal with that when he comes to it.

In the meantime, Stephen Colbert for one clearly believes Mr. Fetterman’s style is the way forward. The late-night host dedicated part of his May 19 monologue to the Pennsylvania race, including a Photoshopped picture of President Biden’s “latest makeover.”

What was it?

Mr. Biden, with a shaved head and goatee, sporting what Mr. Colbert called Mr. Fetterman’s burgundy “formal hoodie.”