The number will be third-quarter GDP growth. The Federal Reserve Bank of Atlanta, the Chicago Fed, the Conference Board, and Goldman Sachs all estimate it will be between 30% and 35%. Even if the real number is substantially lower, it will still be historic. Such an explosion of economic activity in the world’s largest economy is unprecedented in the history of GDP calculations, which goes back to the Great Depression.

Data like that coming five days before a presidential election ought to be a priceless gift to the incumbent. That’s especially true considering that the economy is by far the No. 1 issue with voters. The latest Gallup poll finds that 89% of registered voters consider it “extremely” or “very” important, with little difference between Democrats and Republicans. But in this, as in so many ways, 2020 is different.

That staggeringly large expected growth number is possible only because it was preceded by an economic disaster in the previous quarter, when the economy shrank at a similarly historic 31.4% annualized rate. Growth of 35% in the third quarter isn’t enough to get the economy back to where it was before that cataclysmic second quarter, and not nearly enough to get back to pre-pandemic levels.

The message to voters: “Great news! The hole you’re in isn’t as deep as it used to be.” Not exactly compelling.

Still, Trump could argue that the economy is recovering strongly and is on the right track. But even that argument probably won’t get him far.

The best scenario is set out by Republican strategist Scott Jennings, who thinks a strong growth number would help Trump with a subset of voters already leaning his way. “The voters who are left in the pool are more moderate to conservative, including some suburban Republicans who approve of Trump on policy but not style,” he says. “A last-minute reminder of why they support him—the economy—would help mightily.”

But two problems will blunt even that benefit for Trump. One is time. “It is very difficult to get a boost five days before Election Day,” says Democratic strategist Patti Solis Doyle. “It is just not enough time for news to impact the average voter in the states that matter.”

The other problem is the extraordinary number of votes already cast by mail or in early voting—more than 50 million as of Friday, plausibly reaching 60 million by Thursday. That’s nearly half the total votes cast in the 2016 election. “The math and the clock are just not on Trump’s side,” says Doyle. “Even if we had a full economic recovery by Thursday, I’m not sure it beats the clock.”

The rational way to regard Thursday’s announcement, historic though it will likely be, is that it’s indeed excellent news, but it’s just the first step on a very long road back to the prosperity we once knew.

More must-read finance coverage from Fortune:

• What Wall Street needs from the 2020 election
• Tom Steyer thinks business is missing a big opportunity—and that Trump has done “nothing but whiff”
• Can an A.I. algorithm help end unfair lending? This company says yes
• Procter & Gamble shows that increasing spending during a recession is worth it
• Stocks in “election-sensitive” sectors seem oblivious to which candidate wins. Why?