Editor’s Note: Republican Charlie Dent is a former US congressman from Pennsylvania who served as chairman of the House Ethics Committee from 2015 until 2016, and chairman of the House Appropriations Subcommittee on Military Construction, Veterans Affairs and Related Agencies from 2015 until 2018. He is a CNN political commentator. The views expressed in this commentary are his own. View more opinion on CNN.

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While much of the 2019 election discussion focused on the Kentucky and Mississippi gubernatorial contests and the Virginia state legislative races, there were pivotal countywide races in Pennsylvania that provide a much clearer view of the political realignment we have been slowly witnessing for many years in my home state.

Charlie Dent

The lesson learned from Pennsylvania, which went for Donald Trump in 2016, is the same as for the rest of the country. As a result of his election and performance in office, the suburbs are nearly completely gone for the Republican Party.

When I was first elected to the Pennsylvania House of Representatives in 1990 from an Allentown-based district, Republicans performed very well in the suburbs and dominated rural areas. There were even a few Republicans like me who were winning elections in urban areas and even more Democrats who were successful in rural communities throughout the state and well beyond the Philadelphia region.

But things were slowly changing. In 1990, while I and two other Republicans were defeating entrenched Democratic state House incumbents in the Lehigh Valley, a perennial bellwether and swing region of eastern Pennsylvania, an almost unheard of young man and young woman defeated an entrenched Democratic congressman and Democratic state senator, respectively, from the other side of the state, in the Pittsburgh area. Their names: Rick Santorum and Melissa Hart.

Four years later Rick Santorum became a US senator, and ten years later Melissa Hart gained a seat in the US House of Representatives. These 1990 election results were shocking to the political class at that time. How did five Republicans defy political gravity to win Democratic districts in the midterm election during the Presidency of George H.W. Bush? This should not have happened, but what we were witnessing was an emerging trend.

Southwestern Pennsylvania was strongly Democratic in terms of voter registration but was increasingly receptive to Republican candidates. At roughly the same time in 1992, we were witnessing Republican slippage in the most populous and most Republican collar county outside Philadelphia, Montgomery County, which elected a Democratic congresswoman, Marjorie Margolies Mezvinsky, who replaced the retiring, moderate Republican congressman, Larry Coughlin. That too was a political earthquake.

What does any of this have to do with the election of November 5, 2019? Plenty. In 1990 we had pro-choice Republicans and pro-life Democrats elected to statewide office. Remember Gov. Robert P. Casey, Sr.? Moderate Republicans and conservative Democrats were very much alive and well in the Commonwealth of Pennsylvania.

Back then we often spoke of the “Catholic” or “Casey” Democrat – pro-labor, pro-life, pro-gun; today, we no longer speak this way. In fact, during presidential elections in the 1990s and 2000s in southwestern Pennsylvania there were significant numbers of Democrats who were functional Republicans, and in southeastern Pennsylvania there were many Republicans who were functional Democrats. Today, most of these voters have aligned their party affiliations with their voting habits.

Devastating losses for GOP

Since the 2016 Presidential election we have witnessed an acceleration and the culmination of the Democratic dominance, takeover and sweep of the populous suburban collar counties of Philadelphia.

Bucks, Chester and Delaware counties’ Republican majority Boards of Commissioners fell to the Democrats last Tuesday; Montgomery County lost its board majority several years earlier. North of the Philadelphia collar counties, Lehigh County, which includes Allentown and part of Bethlehem, lost its Republican board majority, as did Monroe County in the Poconos.

These defeats in the Philadelphia suburbs on Tuesday were every bit as devastating as the Republican losses in the Virginia suburbs of Washington, DC, and Richmond, or the Kentucky suburbs of Lexington, Louisville and Cincinnati. And that says something, since northern Virginia Republicans were shut out in the House of Delegates races in the suburban communities of Alexandria, Arlington and Fairfax.

In Pennsylvania, the defeat of the Delaware County commissioners is both stunning and historic, but given the trends, not surprising. Republicans have controlled the board since the Civil War and operated a legendary political machine. Chester County, too, was Republican dominated as far as anyone can remember.

The silver lining for Pennsylvania Republicans on Tuesday was the flipping of six county governments from Democrat to Republican in largely rural southwestern and northeastern Pennsylvania counties. Luzerne County, which twice voted for Barack Obama and by a wide margin for Donald Trump, flipped to the Republican column.

That’s the good news for Republicans, but it pales in comparison to the losses of the large population centers in the counties that went Democratic.

Existential threat

The ever-expanding circle around Philadelphia and other urban population centers poses an existential threat to the GOP. It’s hard to imagine a scenario where Republican losses in the suburbs can be offset by increased gains in rural areas; the math simply doesn’t work.

Yes, the rural areas of Pennsylvania, and America more broadly, are becoming more Republican and red while the suburbs are becoming more blue and Democratic. But it’s better to grow and win in areas where the population is increasing rather than in areas of population stagnation or decline, and that is the key Democratic advantage heading into 2020.

Overall, the Pennsylvania elections of 2017, 2018, and 2019 were very unkind to the Republican Party and the trend does not bode well for next year. 2020 could be another terrible Republican year given President Trump’s high unfavorability ratings that are driven by his increasingly erratic behavior and misconduct in office.

Maybe he can pull another inside straight in Pennsylvania where he won in 2016 by 44,000 votes while losing big in the Philadelphia suburbs. That said, the political environment is worse now than in 2016, making Trump’s Pennsylvania re-election prospects improbable and imperiling down-ballot congressional and state legislative candidates.

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    Of course, the Democratic presidential nominee will also shape and condition the 2020 political environment. If the Democrats were to nominate, say, Sen. Elizabeth Warren or another candidate sharing her extreme views, Donald Trump’s election prospects would rise considerably in Pennsylvania.

    Warren’s plans to ban hydraulic fracking by what would likely be an illegal executive order and impose punitive wealth taxes, and her general hostility toward industrial and agricultural America, will drive even more rural votes to Trump and likely mitigate his losses in suburban communities. Whatever their views of Trump, large numbers of Pennsylvania voters would see Warren as a very real and immediate threat to their economic interests and values.

    Many suburban voters view the Republican brand as too nativist and socially intolerant. If the Republican Party ever hopes to reclaim lost territory in the suburbs and elsewhere, it can start by rejecting isolationism and protectionism, advocating constructive international engagement by reengaging with traditional allies and defending the American-led international order, embracing diversity and inclusion, and striving to become more socially sensible.

    If demography is destiny, then Republicans must get on the right side of it. Otherwise, the results of the 2020 election for the Republican Party in Pennsylvania will make the previous three dreadful elections pale in comparison.