NEW YORK (AP) — The special election in Pennsylvania's 18th district has made one thing clear: Democrats turned a region that overwhelmingly backed President Donald Trump just 16 months ago into a dead heat. It didn't matter that this congressional district will effectively disappear next year. Each side fought hard and spent big knowing that the race would help shape the national political landscape heading into the November midterm elections.

With that in mind, here are the top takeaways as the final votes come in:

RETHINKING A 'SAFE' DISTRICT

Republicans are trying, but there's no way to spin the special election results as anything other than a grim scenario for the Republican Party. Trump won the district by nearly 20 percentage points in 2016. Democrat Conor Lamb's performance in southwestern Pennsylvania means that the GOP's grip on the House majority is in serious peril this fall.

There has been much discussion about the vulnerability of 23 Republicans serving in congressional districts that Trump lost in 2016. They're more vulnerable than ever. But there are 106 other House districts Trump won by less than 20 points, suggesting that scores more Republican-held seats could be in play this fall. Democrats need to flip 24 seats to claim the House majority — just 23 if Lamb wins. Both numbers increasingly look reachable. For GOP strategists, or those members considering retirement, it may be time to hit the panic button.

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TRUMP HITS HIS LIMIT

The president was all-in for Republican Rick Saccone in a region considered solid Trump country. The Republican president visited the district twice on Saccone's behalf. He dispatched his daughter, his eldest son, his chief counselor and his vice president to the district. It wasn't enough to pull out a clear win.

Saccone parroted Trump's message, he said he wanted to be Trump's "wingman," and he benefited from Trump's political operation. It wasn't enough.

This marks the second consecutive special election in which Trump struggled to push his preferred candidate over the finish line. Only this time, unlike Alabama's recent Senate election, he can't blame a candidate saddled with multiple allegations of sexual misconduct.

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DEMOCRATS ARE HOT

Democrats did it in Virginia, New Jersey, Alabama. They did it in a string of lower-profile state house elections in places like Missouri and New Hampshire. Now, they've done it in the heart of Trump country in working-class western Pennsylvania.

As the November midterms grow closer, the energy on the left is as strong as ever. Lamb effectively harnessed that energy with a large get-out-the-vote operation that dwarfed that of his Republican opponent. And Democratic candidates across the country hailed Pennsylvania's result as reason to be even more excited. Rep. Charlie Dent, an eastern Pennsylvania Republican who is retiring at the end of the year, predicted Wednesday that the Democratic wave "is going to be like 2010" — a reference to the anti-Obama wave that cost the Democratic Party 63 seats.

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CANDIDATES MATTER, BUT ONLY SO MUCH

Saccone was an underwhelming candidate. He struggled to raise money. He had a weak get-out-the-vote operation. He didn't spend much time with voters. But it's a mistake to suggest that the Republican state representative's personal flaws alone triggered a 20-point swing in his district.

Saccone didn't make any major gaffes. He avoided the personal scandals that have plagued Republican candidates in other recent elections. And he was remarkably disciplined in a message that embraced Trump, promoted the GOP-backed tax overhaul, and tied his opponent to unpopular Democratic leaders like House Minority Leader Nancy Pelosi. That's roughly the same playbook Republicans are planning to employ in Republican-leaning regions across the country.

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NOT PELOSI'S LITTLE LAMB

Running in a conservative district, Lamb did not run as a typical anti-Trump liberal. He barely talked about the Republican president. He embraced gun ownership. He didn't support House Minority Leader Nancy Pelosi. He didn't necessarily run as a "Republican lite," however, as House Speaker Paul Ryan and other Republicans have suggested.

Lamb ran as an unapologetic Democrat on several key issues: He attacked the Republican tax overhaul, and he also embraced the Democrat's health care law along with Social Security and Medicare. And while he didn't emphasize his liberal positions on abortion and gay marriage, he didn't run from them either. Lamb said he was personally opposed to abortion, but respected the law of the land. It's true that such a message could alienate Democratic primary voters, but Lamb's message could also offer a general election playbook for Democrats running in pro-Trump regions this fall.

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AP writer Stephen Ohlemacher contributed to this report.