CANTON, Ohio (Reuters) - If Donald Trump wins the Republican Party nomination, his path to the White House will run through this working-class city with a knack for picking presidents. No Republican has ever won the White House without Ohio. And nowhere better reflects the challenges and opportunities Trump faces in his 2016 presidential quest than Canton, a once-booming industrial city that, like Ohio and the rest of America’s rust belt, is going through profound economic and demographic change. Canton, a gritty northeastern Ohio city where the once-dominant steel industry has been in decline for 20 years, is the heart of Stark County, a political bellwether that, save twice, has picked every winning presidential candidate since 1964. The real-estate mogul’s primary wins in Michigan and in Mississippi on Tuesday, in the face of blistering attacks from the party’s establishment, expanded his lead in the White House nominating race and demonstrated his broad appeal across many demographic groups in the Republican Party. But here, in predominately white Canton, the birthplace of professional American football, he will need to show cross-over appeal in the general election and win over not just Republicans but working-class Democrats and some independents, to beat a Democrat, illustrating the challenge he will face in Ohio and potentially other Midwestern “rust belt” states. A more immediate test looms next week in the state’s Republican primary, where polls show Trump narrowly leads Ohio Governor John Kasich, who casts himself as a pragmatic, statesman-like alternative to Trump. If Trump wins Ohio and Florida — states rich in the delegates who select their party’s nominee at July’s Republican National Convention -  he would almost certainly lock up his party’s nomination. Sitting in a steel workers’ meeting at their Canton union hall, Curtis Green, the chapter’s vice president, described Trump’s support among a growing number of members as their “dirty little secret.”  “I view him as a radical and a racist and I don’t want to be affiliated with that,” Green said. “But if you say what you mean, a lot of guys see that in Trump and they respect that. He doesn’t dance around the issues, he takes them head on. There are a fair amount of our members who do support Donald Trump.” If Trump just wins the states that Republican nominee Mitt Romney won in 2012, he would have only 206 electoral college votes, short of the 270 needed to win the White House. The fight over electoral college votes has turned recent elections into pitched battles over a dozen or so states.  Ohio is often at the center.  The state, which has not voted for the loser in a presidential election since 1960, is seen as a microcosm of American swing voters — from culturally conservative “Reagan Democrats” who defected from their party to support Republican Ronald Reagan in the 1980s to suburban soccer moms and upwardly mobile Hispanics. To offset the growing proportion of blacks and Hispanics in the voting age population, Trump must turn white voters out in greater numbers than Romney in cities such as Canton. His performance in primary states where Democrats and independent can vote, as well as Republicans, suggests Trump could attract large numbers of these voters in a general election.  Reuters interviews here with more than two dozen voters show why. In this city of 72,500 people, Trump’s denunciation of free trade, political correctness and illegal immigrants is resonating among some traditionally Democratic blue-collar steel workers.  “The labor unions, who usually support the Democrats, a lot of our members, and a lot of their families, are supporting Trump,” said Keith Strobelt, a political director for the United Steelworkers local union in Canton. Strobelt does not support Trump.  Canton’s local United Steelworkers union has 1,800 members - down from 6,700 at its peak 30 years ago. Its leadership has not officially endorsed a candidate, thought it has praised Democrat Senator Bernie Sanders. Some rank-and-file members, however, say they better identify with Trump’s broadsides against illegal immigration and tirades against trade with China and Mexico. “It could be that several hundred of our members will back Trump,” Strobelt said. “A lot find him refreshing. He says a lot of things they say around their dinner tables.” But in a general election, Trump faces formidable odds in Canton, as he does across Ohio and the Midwest. Canton and the region is changing in ways that favor Democrats, reflecting the Republican Party’s broader problems with a U.S. electorate that is becoming less white and less culturally conservative. In 2000, Canton was nearly 75 percent white, with an African American population of 20 percent, and an Hispanic population of just over 1 percent. Its biggest employer was the Timken Company, a giant ball bearing and high custom steel manufacturer that was the dominant economic force in Canton for much of the 20th century. By 2010, according to Census data, Canton was 69 percent white. Its black population had increased by 3 percent, its Hispanic residents to nearly 3 percent. Tuesday’s primary in neighboring Michigan showed how volatile this election has become, with Trump’s potent appeal among disaffected whites stretching beyond the South. In the Democratic race, Sanders won most of the state’s white working-class countryside and small towns in an upset over front-runner Hillary Clinton. In Canton, like elsewhere in the “rust belt” heartlands stretching from the Midwest to the Great Lakes region and parts of the Northeast, manufacturing has been hollowed out since the 1970s, due in part to foreign competition. In 1990, Ohio had over 1 million manufacturing jobs; today, just 680,000, according to the U.S. Bureau of Labor Statistics. Ohio has shed nearly 200,000 manufacturing jobs since the 2007-2009 Great Recession. A different type of worker, more white collar and upscale, has moved into the Canton area.  The top two employers are now the Aultman Hospital and Mercy Medical Center, highly competitive health care providers.  “While Trump might pick up blue collar Democrats, and older folks who are disillusioned with the political process, the flip side is he could lose more upper-status voters in Ohio,” said John Green, a political science professor at the University of Akron, close to Canton. “Republican Party leaders in Ohio are wringing their hands. There is a perception that Trump helps among blue collar voters - but could alienate white collar voters.”   Jane Timken, the vice-chair of the Stark County Republican Party and the wife of TimkenSteel’s chief executive, said the local party was encountering people who had never voted Republican before but were supporting Trump. But, she said, there was concern Trump might turn off other voters, especially independents who account for one fifth of Ohio’s voters.  There is no polling to predict which way Canton and Stark County will vote in November’s general election. But after a long era of mixed local government, the city council, after elections last year, is now made up of entirely Democratic Party members, although the current mayor, a former Democrat, won office as an independent. In Canton, there are nearly 6,000 voters registered as Democrats, compared to just over 1,100 Republicans according to the Stark County Board of Elections. In 2006, there were 12,000 registered Democrats and 4,400 Republicans.  Democratic strategists say that despite the demographic changes, Trump could still prevail. Mary Anne Marsh, a Democratic strategist, cites Trump’s dominant performance in the Republican primary in Massachusetts on March 1. Although not a rust belt state, Trump won big in heavily blue collar, union cities.  “Trump put together a coalition in Massachusetts that elects Democratic governors. He won among Catholics, a week after picking a fight with the Pope. I absolutely think he can put the rust belt into play,” she said. 