Republicans may not be committing political hyperbole this year when they say their presidential candidate can win Pennsylvania, experts say.

Every election since Pennsylvania went for Bill Clinton in 1992, Republicans have declared “this time” the Keystone State will turn red.

And every cycle they fail.

This year might be different, according to experts in electoral math.

“Republicans don't need Pennsylvania to win the electoral vote, but Democrats do, and a loss here for Hillary Clinton on election night would likely mean she loses the White House by the morning,” said Lara Brown, director of George Washington University's political management program.

The key to presumptive GOP nominee Donald Trump's winning Pennsylvania in November lies in just 10 counties, the experts say.

And it all comes down to tweaking the margins in existing red counties rather than flipping traditionally blue counties.

In 2012, Mitt Romney lost to Barack Obama by 309,840 votes. But add a couple of thousand votes in 10 or so counties, and all of a sudden the race gets close.

THE WIDE VIEW

Dave Wasserman, political analyst at the Cook Political report, crunched Pennsylvania's electoral trends since 1996 and concludes the Keystone State could be the tipping point this cycle for the Republicans.

Pennsylvania has become 0.4 percent more Republican every cycle, Wasserman said.

In 1996, 28 of Pennsylvania's 67 counties went for Bill Clinton over Bob Dole; by 2012, just 11 counties went for Barack Obama over Mitt Romney.

Western Pennsylvania has been the driving force in the state becoming more Republican said Henry Olsen, a Senior Fellow at the Ethics and Public Policy Center. Olsen said voting patterns of former union Democrats displaced by trade deals and environmental regulations that impacted the coal industry contributed to the rightward push.

“If you look at the coal county of Greene, the person who is not looking closely says, ‘Oh well, Romney carried it by huge margins, so how can that make a difference for Trump?' Well he did, except potential turnout was down by 10 percentage points,” Olson said.

“If Trump gets that 10 percent back, that is only 1,500 to 2,000 votes in a small county like Greene, but then you get an extra 10 percent in Washington, Cambria, Indiana, Somerset counties, which have larger populations,” he said of neighboring counties with similar voting patterns.

“Then, all of a sudden, you are talking about an extra 200,000 votes; you have to look at turnout and margin as much as who carries it,” he said.

That math does not apply to Western Pennsylvania exclusively.

“The same goes for the Philly collar county of Bucks,” Wasserman said, as well as the northeastern coal counties of Luzerne and Lackawanna, “where Trump won't necessarily win, but could chip away at Clinton's margins.”

Wasserman said while the suburban counties of Pittsburgh neither resemble nor are as populous as the suburban counties of Philadelphia, “Philly's collar counties are not as blue as you would suspect, and Pittsburgh's collar counties need to have a larger turnout to make the difference.”

Trump's performance in the Republican primary was remarkably strong. He swept all 67 counties. That popularity did not appear to abate even after nearly a month of public relations stumbles and bad press, including Trump's comments on an Indiana judge's ethnic background and apparent self-absorption in the aftermath of the Orlando massacre. A Quinnipiac University poll showed Trump remained tied with Democrat Hillary Clinton in Pennsylvania at the end of June.

Sean Trende, election analyst at RealClearPolitics, said Clinton must strongly outperform Obama's 2012 numbers in Dauphin, Chester and Lancaster to win.

Wasserman, Olson and Kyle Kondik at the University of Virginia's Crystal Ball agreed.

In 2012, Obama won Dauphin by 7,000 votes but won Chester by only 500 ballots. He lost Lancaster by 50,000 votes.

“On the flip side of all of this is if Trump turns off some well-off, well-educated Republicans, a county that could flip from Romney to Clinton is Chester, which has both the state's highest median income and the highest percentage of residents over 25 years old with a four-year degree,” Kondik said. “Romney only won it by 0.2 points in 2012.”

THE GOP'S CRITICAL 10

Here are the 10 counties experts identified as critical for a Republican win.

Bucks County: All agreed Bucks is the perfect gauge with the right mix of working class and suburban voters to see how the state is trending.

“Trump is really going to need to increase the share of the vote of the working-class Democrat and independent voters,” Olson said. “They are the sort of person you will see in Lower Bucks. If he is winning them in this county, then he is doing well in Lackawanna, Luzerne and Northampton in the east.”

Greene and Cambria counties: These two counties showed the largest swings toward Republicans from 2004 to 2012, Trende said. But there also was a drop-off of 7,000 votes in 2012. Voters who didn't show up for Romney have to show up for Trump to offset heavily Democratic Philadelphia's large population, Trende said.

Washington and Westmore­land counties: “Washington and Westmoreland counties have been going Republican since 1996, but they need to go in a bigger way for Trump to win,” Olson said.

Westmoreland is more of a suburban county and Washington is home to voters who would have been blue-collar Democrats 30 years ago, he said.

“Of the two, you are likely looking at Washington, where you are going to be likelier to find the increase in turnout and the swing toward Trump that he is going to need,” Olson said.

Lackawanna County: This county is going to go Democratic, but it is one of Trump's biggest county wins in the Republican primary, Wasserman said.

Instead of losing by more than 20 points, Wasserman said losing by 15 points or less could help Trump carry the state. “This would be one to look at the margins,” he said.

Luzerne County: “This county is traditionally Democratic, but can Hillary bring that home with the economic and social issues tugging at her? This could be the year it goes for Trump,” Wasserman said.

Clinton bested rival Vermont Sen. Bernie Sanders by fewer than 2,000 votes in the Democratic primary. What's more, that's 27,000 fewer votes than she received in the 2008 Democratic primary.

“Luzerne is a useful county to watch,” Kondik said. “It is not prosperous and has a fairly high percentage of white residents. If Trump is re-writing the state's playbook, that would seem like a county he could potentially carry.”

Dauphin County: “This county showed the largest swing in the state from Kerry to Obama; if it moves back, that suggests a large portion of the Obama phenomenon was Obama-specific,” Trende said.

York and Lancaster counties: “The triangle of Lancaster, Dauphin and York are the fastest-growing Hispanic population in the state, albeit still smaller than national trends,” Wasserman said. Clinton's success relies on her ability to reach out to this community.

“If we start seeing voters in these 10 counties leaning (toward) Trump, we may be looking at something bigger — a new political realignment for both parties across the country,” Brown said.

Salena Zito is a Tribune-Review staff writer. Reach her at szito@tribweb.com.

Salena Zito is a Pittsburgh Tribune-Review editorial page columnist. E-mail her at szito@tribweb.com