DEBATE DAY BRINGS BAD NEWS FOR BIDEN. It’s only natural for pollsters and other political professionals to try to take the public’s temperature about a presidential race right before a big debate. The debate might have little effect on the race, or it might change everything, and the only way to know is to measure where the race was immediately before the event.

So, on Wednesday, we saw a wave of new polls and analyses that added up to terrible news for the campaign of President Joe Biden. The short version is that the race could be returning to the state it was in before former President Donald Trump’s trial and conviction in Manhattan. For a few weeks after the guilty verdict, it appeared that the contest, in which earlier this year Trump had a lead of between one or two points in the RealClearPolitics average of national polls, had, after the conviction, narrowed to less than one point, or perhaps Biden pulling ahead by a slight margin, as happened in the fivethirtyeight.com average.

“Yes, heads are exploding all over MAGA land today,” wrote the Democratic strategist Simon Rosenberg on June 20. “As I’ve been writing over the past few weeks, there are now many serious, credible polls showing recent movement to Biden. Like the [June 19] Fox poll, many also now have Biden leading.” On June 22, Rosenberg wrote, “On 538 Biden now leads in the national popular vote and in Michigan and Wisconsin. As we’ve been discussing this week, the election is changing now and President Biden has been gaining in a wide variety of polls.”

There’s no doubt many Democrats hoped to reap a political benefit from the Democratic prosecution of Trump in New York. And after Trump was found guilty on 34 felony counts, in a case Republicans and some independents dismissed as politically motivated, that benefit seemed to appear.

But the optimism may be short-lived. On Wednesday, Quinnipiac released a new poll showing Trump ahead of Biden by four points among registered voters, 49 to 45, in a national head-to-head matchup. Just a few weeks ago, on May 22, after five weeks of the Trump trial, Quinnipiac’s numbers showed Biden slightly ahead, 48 to 47. A month earlier, on April 22, in the first week of the trial, Quinnipiac had the race tied. Now, Trump is leading.

Then, also on Wednesday, the New York Times and Siena released a new survey showing Trump leading Biden by six points among registered voters, 48 to 42. The Times did not poll during the trial, but just before the trial, one of their polls found Trump in the lead by a single point. Now, Trump’s lead appears to have grown.

The Times survey also contained a number that might be even more concerning for Democrats. It found Biden’s job approval rating to be 35%, versus 61% disapproval. Now, that might be a little low — the RealClearPolitics average of job approval polls is 40% — but 35 percent, even if if just indicates a downward tick in Biden’s job approval rating, is terrible news for a president seeking re-election.

Then the Washington Post published a new analysis of existing polls with the headline, “Trump leads in 5 of 7 states most likely to determine the election, polling averages say.” The Post concluded that, at the moment, Trump leads in Georgia, Arizona, and Nevada, all by five points, North Carolina by 4 points, Michigan by three points, and is behind Biden by less than a point in Wisconsin, while Pennsylvania is tied.

Finally, also on Wednesday, the influential poll analyst Nate Silver published a piece headlined, “The presidential election isn’t a toss-up,” noting that yes, either Biden or Trump could win, “but the odds are in the ex-president’s favor.” Using a wildly complex model of analyzing data, Silver concluded that, at the moment, Trump has a 66% chance of winning. Now, we will see whether the debate changes that, although just like with any other major news event, we’ll need to give it a week or to set in the public’s mind and show up in reliable polls.

One extremely important thing to remember is that all this could change. It always can with polls. But the latest results are simply not what Democrats had hoped to see after the elected Democratic district attorney of Manhattan took Trump to trial and won. Ever since the May 30 verdict, Democrats have called Trump a “convicted felon” over and over and over. In Atlanta, site of the debate, the Democratic National Committee purchased five big billboards — five of them — with a picture of Trump’s mugshot and the message: “DONALD, WELCOME TO ATLANTA FOR THE FIRST TIME SINCE BECOMING A CONVICTED FELON. CONGRATS — OR WHATEVER.”

That’s a pretty clear sign of where Democratic hopes lie these days. But this new round of polling is not the news they wanted to hear.