Democrat Pat Ryan was considered the underdog in Tuesday’s special House election for New York’s 19th District – but a combination of good timing, old-school politicking and favorable turnout pushed the Ulster County executive to a surprise victory many experts see as an indicator of how the November midterms could go across the country.

“I don’t think there’s enough Pepto-Bismol in all the CVS’ in the nation to calm Republican nerves,” political consultant Bruce Gyory told The Post.

“For Ryan to hold this district in a special election is a further indication that this midterm election is going to have surprises and no party should rest easy,” he added.

While pre-election polls showed Ryan trailing Republican Dutchess County Executive Marc Molinaro, the Democrat pulled off a win by two percentage points in the special, held on the same day as party primaries for Congress and the state Senate.

Ryan lost nine of NY-19’s 11 counties, but still got 3,000 more votes than Molinaro thanks to a 9,179-vote cushion in Ulster County alongside a 2,322-vote margin of victory in exurban Columbia County.

Total turnout in the special election was 25% districtwide – but was higher in the two counties Ryan won. About 70% of voters in the district also cast ballots in 2020, while 59% voted in 2018. Just 13% of Ulster County voters took part in the 2019 special when Ryan was first elected county executive, while 29% voted Tuesday.

Molinaro conceded defeat Wednesday while suggesting the timing of the special election contributed to his loss in the 19th district, which includes parts of the Hudson Valley and Catskills.

“We knew this was an uphill battle when Democrats scheduled this special election on the same day as two Democratic Primaries with five candidates pushing their turnout,” he said.

Ulster County Democratic Committee Chair Kelleigh McKenzie told The Post Wednesday that a “neighbor-to-neighbor” approach to campaigning helped drive loyal Democrats to the polls in the unexpected summertime contest to replace former Rep. Antonio Delgado, who resigned to become lieutenant governor this spring.

“We were all so excited after what happened in Kansas, and we knew that we could do it here,” McKenzie said, referring to a recent anti-abortion ballot initiative that went down in flames in the Sunflower State after the Supreme Court struck down its landmark Roe v. Wade decision on abortion rights.

“That message of hope across the country really motivated people to go that last mile and make those extra 200 calls and everything,” McKenzie added.

The NY-19 success has fueled hopes among Democrats that they might hold onto their slim majority in the House of Representatives, despite political headwinds like rising crime and prices — as well as historical midterm trends that run against parties in power.

But Republicans say the special election results only reveal so much about what will happen in November.

“There’s some significance to it, but I think that the combination of two congressional primaries underneath this special as well as the difficulty of turning people out in an August special election works against the Republicans here,” former Rep. John Faso, who lost the seat to Delgado in 2018, said Wednesday.

“The existing New York-19 has almost 20,000 more [registered] Democrats than Republicans so it’s a difficult seat, as I can attest,” Faso added.

Ryan, who will hold the seat through the remainder of the year, campaigned heavily on support for abortion rights and gun control while blasting Republicans like Molinaro as extremists in line with former President Donald Trump.

Molinaro countered by pointing to inflation and bail reform as reasons why voters ought to flip the district red for the first time since Delgado won it in 2018.

“Message: crime is a downstate problem. Abortion – a woman’s right to choose [remains] an anchor around Republican necks,” political consultant Hank Sheinkopf told The Post in text message Wednesday.

Republicans are hoping to bounce back and flip control of the House with a win by Molinaro in a newly-redrawn District 19 – but political experts say they’d better come up with a way to counter Democratic messaging on abortion or risk losing more elections they might otherwise win.

“The Hochulmander mess included a special election with two Democrat primaries inside it, fueling one-sided turnout and massive voter confusion, but even despite that, Democrats only managed to hang on by a slim margin in a blue seat Biden won,” state Republican Party Chairman Nick Langworthy said in a statement. “We have every confidence that Marc Molinaro will be elected to Congress this November.”

But political experts say they’d better come up with a way to counter Democratic messaging on abortion or risk losing more elections they might otherwise win.

“We’re always looking for bellwethers to see which way the wind is blowing. And this is one that meets that criteria,” Larry Levy, executive dean of the National Center for Suburban Studies at Hofstra University, told The Post.

“You could justifiably say that this was not just a fair fight, but one that was determined on issues and I don’t think there’s anybody who would tell you that Ryan would have won this two months ago.”