CNN has Trump nipping at Biden’s heels. ABC has Biden cruising. The truth is in the middle.

A new CNN poll released on the eve of the Democratic National Convention indicates that the lead presumptive Democratic nominee Joe Biden has enjoyed over President Donald Trump in most national polls all but evaporated in recent weeks. But another one released hours later by ABC and the Washington Post illustrated why. It’s important to put any single survey in context.

A poll conducted by CNN in June had Biden up by a robust 14 percentage points. But the new poll released Sunday showed his lead among a random national sample of adults slimmed all the way down to just 4 percent — a spread nearly within the poll’s 3.7 percent margin of error.

“Across 15 battleground states, the survey finds Biden has the backing of 49 percent of registered voters, while Trump lands at 48 percent,” CNN’s writeup of the poll says, though it doesn’t identify which specific states were included in that set.

Some understandably responded to the poll with surprise that a race that seemed Biden’s to lose could suddenly be so close, especially as the coronavirus continues to rampage out of control and with the unemployment rate north of 10 percent.

Others, however — like Greg Sargent of the Washington Post — quickly pointed out that the CNN survey has all the makings of an outlier.

Sargent’s view was quickly vindicated. The ABC News/Washington Post poll of a random national sample of adults released Monday morning showed Biden with a 12 percentage point lead over Trump (margin of error 3.5 percent) — a spread more in line with the polling averages like RealClearPolitics and FiveThirtyEight showing his advantage in the range of 8 percentage points.

So Biden appears to still be favored by voters. But Trump remains in striking range given the structural advantage that the Electoral College gives to Republicans.

Biden’s lead has actually stayed remarkably consistent over time

Aggregations like those put together by RealClearPolitics and FiveThirtyEight are only as good as the polls they aggregate. But since any single poll can be off by three or four percentage points, the 30,000-foot view polling averages provide is a better way to get a sense of a race than by drawing conclusions from single data points like the CNN survey showing the race in doubt or the ABC/Post poll showing Biden cruising to a blowout.

The truth of where the race currently lies is likely somewhere in the middle. With both the CNN and ABC/Post polls included, FiveThirtyEight’s daily polling average shifted from an 8.5 point Biden advantage on Sunday to an 8 point advantage on Monday. In short, Trump may have narrowed the gap slightly, but Biden is still solidly ahead in the polls.

In fact, as Sargent noted citing FiveThirtyEight’s polling aggregation, what’s stood out about the Biden-Trump contest so far is how stable Biden’s lead has been.

It wouldn’t take much to throw the race in doubt, however.

As Hillary Clinton can attest, Biden leading in the polls and perhaps winning the popular vote doesn’t mean he’ll be the next president. But as my colleague Ian Millhiser has explained, if Biden ends up winning the popular vote by six points or more — which he would do if the results of election day mirror current polling — it’s extremely unlikely that Trump could claim enough swing states and once again prevail in the Electoral College.

Still, election day may not reflect this summer’s polls. As my colleague Li Zhou has explained, polls are snapshots in time rather than predictive tools — and many factors, from low turnout to trouble with mail-in ballots, could mean November’s results look radically different than polling currently suggests they will.

Trump is desperate for wins because he’s losing

All caveats aside, the CNN survey is as close as Trump has been to Biden in a reputable survey in quite some time. So the president predictably took to Twitter to tout it as a major indicator of momentum, contrasting it favorably with a Fox News poll released last week that showed Biden up by 7 percentage points.

Trump, of course, regularly dismisses polls more in line with polling averages, insisting that 2020 will see a reprise of the sort of “fake polls” that showed Clinton beating him in 2016.

That seems unlikely. As Zhou notes, pollsters have tried to correct for errors they made in 2016, working to include more representative samples, and adjusting their results to account for factors — like educational disparities — in ways they previously did not.

And overall, the idea that polls in 2016 — particularly national ones, like CNN’s — were way off isn’t completely accurate. For instance, FiveThirtyEight’s final election forecast had Clinton besting Trump in the popular vote by a 48.5 percent to 44.9 percent margin — a spread very close to Clinton’s actual margin (48.2 percent to 46.1 percent).

Clinton’s largest national FiveThirtyEight lead of that cycle came in August, when she was up 49.1 percent to 41.7 percent against Trump — a spread very similar to Biden’s current lead over Trump. So a lot can still happen between now and November. But right now, at least, the idea that Trump is nipping at Biden’s heels isn’t borne out by a full accounting of the data.

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