It’s a gauge of Pennsylvania’s importance that the betting odds of him winning that state and the betting odds of him winning the election have mirrored each other closely (with both bouncing around between 35% and 40% of late). As the Keystone State trends, so do Trump’s odds, almost point by point. In betting on scenarios in which the election is decided by a single state, Pennsylvania is also handicapped as twice as likely to be the decider than second-place Wisconsin.

In recent days, Trump’s poll numbers in the Pennsylvania were dropping, and that drag was the principal reason for his dwindling prospects on the political gambling sites. But last night’s debate saw a shift in Trump’s favor. Minute-by-minute data provided to Fortune by the major betting site PredictIt shows that the shift started in the last 20 minutes of the debate, when Trump and Biden clashed over energy. In the contest’s most dramatic exchange, Trump demanded, “Would you close down the oil industry?” Biden parried, “I would transition from the oil industry.” Trump fired back, “That’s a big statement,” and the former vice president declared, “That is a big statement.”

Minutes later, Biden added, “The oil industry pollutes significantly. It has to be replaced over time.”

Trump was obviously hoping to goad Biden into going big by taking a clear, outspoken position on his opposition to fossil fuels. That’s what happened. The question is whether the former VP’s double-down will galvanize even more of the hundreds of thousands of Keystone State voters whose livelihoods depend on fracking to go to the polls on Nov. 3. And if those voters turn out in force, will Biden win enough votes in the Philadelphia suburbs, where people like his climate-friendly policies, to offset all or most of any losses in the Western coal regions?

It’s instructive to compare betting odds on both the national scale and for Pennsylvania before and after the debate. On PredictIt, at 9 p.m. Eastern time, just before the two candidates faced off, Biden was the favorite by 61% to 39%. At 11 a.m. on Friday, the numbers were precisely the same, holding Biden’s edge pretty much where it’s been for the past couple of weeks. In the RealClear Politics average of gaming sites, Trump got a tiny lift, going from 35.4% to 36.3% from Oct. 22 to 23. Betfair gave Trump his biggest boost, but that two-point lift raised his line to just 34%.

In Pennsylvania, however, Trump gained ground—albeit in more of a shuffle than a jump. The morning of the debate, Biden led Trump on PredictIt by 64.5% to 35.8%. By the end of the debate at 10:30 p.m. ET, his advantage had shrunk, 63.1% to 37.9%. By Friday morning, the President hit almost 39% to Biden’s 61%, though Trump had fallen back to 37.5% by noon. Still, the President had gained almost two points from his pre-debate numbers.

It’s fair to wonder if the “I’m for fossil fuels” boost would have to be far bigger if Trump is to win reelection.

Krishnamurty thinks that Trump made some progress in Pennsylvania: “He did much better than in the other debate, and Republicans are delighted that they get a dividing line from Biden on energy. That was smart politics.” But he notes that “Biden did a competent job of appearing a vanilla, stable, unifying candidate.” He forecasts that Biden will carry Pennsylvania, “the decider,” despite Trump’s gains there from the debate.

So Krishnamurty doesn’t see a surge in momentum in the Keystone State that could put Trump over the top. Charlie Gerow, a top Republican strategist who heads Harrisburg consultancy Quantum Communications, sees it differently. He believes a Trumpian wave that was already underway will hit a new gear because of what he characterizes as Trump’s checkmate in the debate. “Joe Biden’s war on oil and natural gas is a political killer for him,” says Gerow. “We’re taking about 1 million endangered jobs.” So far, the shift to Trump is small. Still, as Gerow says, the issue is large in the state that matters most. The betting odds will soon be showing us how large.