John Fetterman’s resounding victory in the Democratic Pennsylvania Senate primary was not surprising, but it was uncharacteristic.Pennsylvania Democrats do not ordinarily veer too far from the center lane, and they are cautious about whom they send forward from their primary elections to take on Republicans in general elections. They’re not gamblers, and given the state’s perennially up-for-grabs status and its unforgiving electoral math, you could argue they shouldn’t be.But on Tuesday, Democrats made Mr. Fetterman, the state’s lieutenant governor, their nominee to compete for the seat being vacated by the retiring Republican Pat Toomey. (They did it despite Mr. Fetterman’s recent health scare; last week he suffered a stroke, but he said that he was on his way to “a full recovery.”)Conor Lamb, 37, a Pittsburgh-area congressman, would have been a more conventional choice. His House voting record tracks to the center, and he has been compared to the state’s three-term Democratic senator, Bob Casey, a moderate and the son of a former Pennsylvania governor.Mr. Fetterman, 52, offers something different, a new model for Pennsylvania. It is built on quirky personal and political appeal rather than the caution of a traditional Democrat in the Keystone State. With over 80 percent of the votes counted, Mr. Fetterman was more than doubling the total of Mr. Lamb, whose campaign, despite winning many more endorsements from party leaders, never gained momentum.For Democrats, the stakes are high: The outcome may well determine the balance of the evenly divided U.S. Senate, future votes to confirm Supreme Court nominees and much else in our bitterly divided nation.Nearly every story about Mr. Fetterman points out his 6-foot-8 frame, shaved head, tattoos and preferred attire — work clothes from Carhartt, a brand long favored by construction workers and miners and more recently by hip-hop artists. He sometimes attends public events in baggy gym shorts.It is all part of a style that has won him passionate followers among progressive Democrats. Mr. Fetterman has been a frequent presence on MSNBC and is a skilled social media practitioner, with over 400,000 Twitter followers. (His dogs, Levi and Artie, have their own Twitter account and more than 25,000 followers.) It can sometimes seem that he skirts the line between being a traditional candidate and an internet influencer.“Fetterman doesn’t have supporters so much as full-on fans,” The Philadelphia Inquirer noted during the campaign. “Fans who write songs about him, buy his merch and know his life story.”Mr. Fetterman has served as lieutenant governor since 2019 and, before that, for four terms was the mayor of Braddock, a town east of Pittsburgh with just over 1,700 residents. He vows to conduct a “67-county campaign” — the whole of Pennsylvania.Rebecca Katz, his senior political adviser, told me that she believes the campaign’s mantra of “every county, every vote” is being received with too much skepticism and said that people “haven’t seen what kind of map he can run on in Pennsylvania.”But he still must solve the math of an evenly divided state: A Democrat hoping to win in Pennsylvania has to thread an electoral needle.Mr. Fetterman will face either the celebrity doctor Mehmet Oz or the financier David McCormick.In the fall, Mr. Fetterman will need to pile up huge winning margins in Philadelphia and Pittsburgh and win by healthy margins in their suburbs and the state’s few other pockets of blue in order to withstand the lopsided totals that Republicans win nearly everywhere else.In less populous counties, as recently as 2008, Barack Obama took 40 percent of the vote or more, but as polarization has increased, Democrats have struggled to get even 25 percent.State Democrats hoped that Joe Biden, a Pennsylvania native and senator from neighboring Delaware — and a white septuagenarian running in a state that is whiter and older than the national average — could reverse that trend. But he did only marginally better than Hillary Clinton four years earlier, cutting the margins by a couple of percentage points but hardly reversing the trend of Democrats being routed in the smaller counties.That Mr. Biden could not do better outside the cities and close-in suburbs has made many Democrats pessimistic about what’s possible in those areas. Mr. Fetterman’s background, his attention to the state’s rural communities and his manner — the work clothes, a straightforward speaking style — could make some difference. In the winning Fetterman model, he narrows the massive margins that have been run up by Republicans.His positions do not differ that much from more traditional Democrats’, but some of his central concerns do set him apart. A signature issue has been the legalization of marijuana — “legal weed,” as he calls it. He has flown a flag displaying cannabis leaves from the official lieutenant governor’s office, alongside a rainbow-colored L.G.B.T.Q. banner.The advocacy of legal marijuana may be the rare issue that draws support from unpredictable corners and crosses all kinds of lines — including urban and rural.The lieutenant governor in Pennsylvania has few defined duties, but as chairman of the Board of Pardons, Mr. Fetterman modernized an outdated system and granted clemency in cases where it was long overdue.Mr. Fetterman’s one glaring departure from progressive causes, and a nod to Pennsylvania realpolitik, is that he does not support a ban on fracking, the environmentally questionable hydraulic extraction of natural gas. Tens of thousands of Pennsylvanians have benefited financially from it by selling drilling rights on their land, working in the industry or both.Mr. Fetterman’s most worrisome vulnerability is his appeal to his party’s most dependable voting bloc: Black voters in Philadelphia and the state’s other urban centers, the places where any Democrat running statewide must mine the largest trove of votes. Only about 10 percent of the state’s voters are Black, but they are an essential component of the margins that the party runs up in the cities.Mr. Fetterman’s challenge stems in large part from a 2013 incident in Braddock, when he used his shotgun to stop a Black jogger and detained him until police arrived. Mr. Fetterman, who was mayor at the time, told police he had heard gunshots in the area and suspected the jogger. Police searched the man down and released him after they found no weapon.The incident has come up during the campaign, and Mr. Fetterman’s responses have been awkward, at best.“He has said he did not actually point the gun, but what difference does that make?” said Mark Kelly Tyler, the pastor of Mother Bethel African Methodist Episcopal Church, one of the nation’s oldest A.M.E. churches. “Even if he admitted that it was from his implicit bias and says that he has learned from it, that would actually be better. It would be accepted.”Mr. Tyler said that if Mr. Fetterman does not do a better job of explaining it, the incident will be “weaponized on Black talk radio and elsewhere” and used by his opponent in the fall to depress turnout.Mr. Fetterman won by huge margins all across Pennsylvania, with one notable exception: Philadelphia. There, it was a close race against a third Democratic primary candidate, Malcolm Kenyatta, a city resident and the first Black openly gay L.G.B.T.Q. member of the state legislature.With the primary complete, everything is reset. In a big state with six television markets, the candidates will likely combine to spend $200 million or more — much of it, undoubtedly, in an attempt to label each other as too extreme for middle-of-the-road Pennsylvania.Mr. Fetterman’s progressive politics and persona appeal to younger people. They lean to the left and are always potentially influential in any election. But they are also traditionally the least reliable voters, especially in nonpresidential years.In Pennsylvania and all other battleground states, it always comes down to the math. The state’s graying electorate does not always like new things or ideas.Mr. Fetterman is ultimately going to have to go where the votes are. And if he has a problem with Black voters, he will have to solve it.Michael Sokolove, a contributing writer for The New York Times Magazine, is the author of “Drama High: The Incredible True Story of a Brilliant Teacher, a Struggling Town and the Magic of Theater,” which is set in his hometown, Levittown, Pa.The Times is committed to publishing a diversity of letters to the editor. We’d like to hear what you think about this or any of our articles. Here are some tips. And here’s our email: letters@nytimes.com.Follow The New York Times Opinion section on Facebook, Twitter (@NYTopinion) and Instagram. More