After decades as one of America’s most reliable political bellwethers, an inevitable presidential battleground that closely mirrored the mood and makeup of the country, Ohio is suddenly fading in importance this year.
Hillary Clinton has not been to the state since Labor Day, and her aides said Thursday that she would not be back until next week, after a monthlong absence, effectively acknowledging how difficult they think it will be to defeat Donald J. Trump here. Ohio has failed to keep up with the demographic changes transforming the United States, growing older, whiter and less educated than the nation at large.
And the two parties have made strikingly different wagers about how to win the White House in this election: Mr. Trump, the Republican nominee, is relying on a demographic coalition that, while well tailored for Ohio even in the state’s Democratic strongholds, leaves him vulnerable in the more diverse parts of the country where Mrs. Clinton is spending most of her time.
It is a jarring change for political veterans here, who relish being at the center of the country’s presidential races: Because of newer battleground states, Mrs. Clinton can amass the 270 electoral votes required to win even if she loses Ohio.
“Their map is a little different, and Ohio is not as crucial as it once was,” conceded James Ruvolo, a former chairman of the Ohio Democratic Party who lives in the Toledo area, a Democratic bulwark that Mrs. Clinton has not visited once this year. “They’ll keep putting in money, but I don’t think they’re going to put a lot of her time in here.”
Ohio has long basked in the presidential spotlight. Every four years, fall would bring frequent candidate visits, ceaseless television commercials and breathless, county-by-county tallies of its voting returns late into election night. Democrats in the state got used to rock concert-style rallies, like the ones John Kerry staged in Cleveland and Columbus with Bruce Springsteen in 2004 and President Obama held at Ohio State to kick off his 2012 re-election campaign. Mr. Obama held five events over three trips to Ohio in September 2012 alone.
And it was all for good reason: No candidate of either party has won the White House without carrying Ohio since John F. Kennedy in 1960.
But its Rust Belt profile, Mr. Trump’s unyielding anti-trade campaign and Mrs. Clinton’s difficulty energizing Ohio’s young voters have made it a lesser focus for Democrats this year, even as it remains critical to Mr. Trump’s path to the White House. As Mrs. Clinton’s aides privately note, the demographic makeup of Florida, Colorado and North Carolina, which have a greater percentage of educated or nonwhite voters, makes those states more promising for Democrats in a contest in which the electorate is sorted along bright racial and economic lines.
And with a once-competitive Senate race in Ohio turning into a rout for Rob Portman, the Republican incumbent, Democrats can quietly pull back from the state with little fear of down-ballot consequences.
As the place where Appalachia meets the Midwest, and where industrial centers arose not far from a vast farm belt, Ohio has prided itself on being a version of America writ small. Its immigration patterns reflected that, with New Englanders resettling here, followed by Germans and eventually Eastern Europeans. At the same time, Southerners, white and black, crossed the Ohio River in search of freedom and opportunity.
But even some of the state’s proudest boosters acknowledge that Ohio, which is nearly 80 percent white, is decreasingly representative of contemporary America.
“Ohio, like a melting iceberg, has slowly been losing its status as the country’s bellwether,” said Michael F. Curtin, a Democratic state legislator and former Columbus Dispatch editor who is co-author of the state’s authoritative “Ohio Politics Almanac.”
He continued: “It’s a slow melt. But we have not captured any appreciable Hispanic population, and there has been very little influx of an Asian population. When you look at the diversity of America 30 to 40 years ago, Ohio was a pretty close approximation of the country. It no longer is.”
What is less clear than the racial trends is whether the state will continue to grow more forbidding for Democrats in future presidential races. That could be determined by the choices the national parties make after the election, particularly whether Republicans continue Mr. Trump’s project of shifting from a business-friendly to a more populist approach on immigration and trade.
“If the Republican Party looks more like the Trump coalition and the Democratic Party looks more like the Obama coalition, then the states Democrats must win will no longer be Ohio and Iowa,” said David Wilhelm, a manager of Bill Clinton’s first presidential campaign and a former Democratic national chairman who lives in suburban Columbus. “They will be Virginia, North Carolina, Arizona and Georgia.”
Yet that same Obama coalition was enough to hand the president a two-point victory in Ohio in 2012, when the state’s demographics were no less challenging for Democrats. The difference now, Ohio voters and strategists from both parties say, is in the two candidates and the issues at hand.
Facing Mitt Romney, who was easily caricatured as a country club Republican, Mr. Obama battered him as a handmaiden for the wealthy and criticized his opposition to the auto bailout, which lifted Mr. Obama with white union Democrats in car-making communities around Youngstown and Toledo.
But this year, Republicans have put forward a candidate whose views on trade are indistinguishable from, if not more hard-line than, the A.F.L.-C.I.O.’s.
“Republicans used to run on God and guns,” Mr. Ruvolo said. “Well, Trump added a third element: trade.”
Paired with Mr. Trump’s jeremiads about immigrants’ taking American jobs, it makes for a powerful combination in a state that has suffered from the decline of manufacturing. Though he lost the Ohio primary to Gov. John Kasich, Mr. Trump still carried a stretch of counties along the eastern spine of the state, its most economically depressed region, where thousands of industrial and coal-mining jobs have been lost. Mr. Trump is expected to pile up significant margins in those counties in November.
Some political veterans speak with wonder about private polls showing Mr. Trump leading even in bedrock Democratic communities. “I see, at best, lack of enthusiasm in traditional Democratic areas,” said Dennis E. Eckart, a former Democratic congressman from suburban Cleveland.
Mike Dawson, a Republican strategist who runs a website on Ohio’s political history, said Mr. Trump would be competitive in two counties in Youngstown’s Mahoning Valley that the Democratic presidential candidate has carried in every election for 60 years with the exception of 1972.
It is no coincidence that the same region kept re-electing Representative James A. Traficant Jr. from 1985 to 2002, despite his routine flouting of ethics. Mr. Traficant, a longtime Democrat who died in 2014, was known for mixing inflammatory rhetoric, a squirrel-like toupee and a hard-edge populism.
“There is not a dime’s worth of difference, as George Wallace once said, between Jim Traficant and Donald Trump,” said Mr. Eckart, whose district abutted Mr. Traficant’s. “They say anything, do anything, just act outrageous, and people just kind of like that.”
Mrs. Clinton remains strongest in the more affluent and educated areas around Ohio’s population centers — Cleveland, Columbus and Cincinnati — where some voters who backed Mr. Romney four years ago are appalled by Mr. Trump.
Emily Huber, a 29-year-old evangelical Christian and loyal Republican in Columbus, is one of them. As she sold candles and jewelry made by victims of sex trafficking at a farmer’s market in the shadow of the state capitol, Ms. Huber said she and her husband were unsure whether they could back Mr. Trump because of offensive comments that she said “show his true character.”
What will determine who wins Ohio, said Representative Steve Stivers, a Republican, is if “Hillary can pick up a bunch of voters in the suburbs to offset the rural and some of the industrial areas.”
Mrs. Clinton has an organizational advantage, with 60 offices across the state, and is flooding Ohio with surrogates: Bill Clinton is expected in the state on a bus tour next week. But her campaign is sensitive about her absence, which has become a local topic of discussion. After this article was published online, it hurried to announce that she would return on Monday, though without specifying which city she would visit.
A Clinton victory in Ohio may also require rousing younger voters, which is in doubt. When a group of Democratic Ohio mayors campaigned recently for Mrs. Clinton in Athens — home of Ohio University and seat of the county with the state’s largest percentage of millennials — they drew little interest.
As students stopped at sidewalk A.T.M.s to prepare for parents weekend, they expressed only lukewarm support for Mrs. Clinton. Paula Atfield, a freshman from Cleveland, said she was voting for Mrs. Clinton because “she’s not Trump,” but added that the election was seen as “a joke” on campus.
“Neither of them are suitable,” she said. “Most people aren’t even voting.”
At a news conference earlier in the day, the Dayton mayor, Nan Whaley, had buoyantly declared that the state would send Mrs. Clinton to the White House. “Ohio is the decider of presidents,” she said.
But now, Ms. Whaley sounded less bullish. “I think it’s crucial,” she said of a Clinton victory in Ohio, before quickly adding of Mr. Trump, “It’s just not as crucial as his.”