North Carolina 9th district Republican congressional candidate Dan Bishop waits to speak with the White House at his victory party in Monroe, N.C., Tuesday, Sept. 10, 2019. (AP Photo/Nell Redmond)

WASHINGTON — North Carolina's special election results are flashing 2020 warning signs for Republican President Donald Trump — and also for his Democratic foe, whoever that turns out to be.

Even though Republicans won Tuesday's race for a House seat, the narrow victory for Dan Bishop underscored the president's problems with suburban voters who took a chance on Trump in 2016 but seem to be shifting toward Democrats. In Charlotte's sprawling Mecklenburg County, there was a 14-point swing toward the Democrats, and there are many similar suburbs across Michigan, Wisconsin and Pennsylvania battlegrounds that will be key to Trump's reelection.

At the same time, Democrats are watching uneasily as rural voters slip further away, hardening the political realignment of 2016 when Trump peeled off disgruntled Democrats to build his base.

Special elections are always unique, experts say. This one, on a sleepy late-summer Tuesday with relatively few people focused on politics, can hardly foreshadow next year in any deep way. But both parties poured millions of dollars into it, and they're trying to read the outcome's signs for 2020.

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North Carolina 9th district Republican congressional candidate Dan Bishop celebrates his victory in Monroe, N.C., Tuesday, Sept. 10, 2019 with his son Jack, left, and wife Jo. (AP Photo/Nell Redmond)

"What's at stake is suburban voters," said Rick Tyler, a Republican operative. Trump's coalition appears to be shifting as suburban women move away from the president, he said. Less clear is if they're decidedly turning to Democrats.

"That ought to worry Trump, and it ought to worry Democrats," he said.

Other Republicans say that some regions appear to be going "Trumpier," as one strategist put it, and big turnouts of rural voters can offset losses in the suburbs. Also, GOP deserters will be fewer if Democrats pick a presidential nominee — Elizabeth Warren or Bernie Sanders — who will be portrayed as too liberal.

"We don't really look at it as suburban-versus- rural areas or whatever," said Chris Carr, the political director of the Trump campaign and the Republican National Committee. He said the party has moved away from geographic targeting and is more focused on turning out individual voters.

"So there's a new math there," said Trump campaign adviser Bill Stepien. "And I think we need to throw out the old way we look at how elections are won and lost."

But is that just wishful thinking?

David Wasserman, an analyst for the Cook Political Report, said the results from Tuesday show there's a "five-alarm fire" for Trump in the suburbs. But there's also a "real constituency" of Trump Democrats in the more rural regions.

The divide between the suburbs and the rural voters is "going to be wider" in 2020, he said.

"We just don't know who that benefits."