On Wednesday afternoon, Quinnipiac University released a new national poll looking at the 2020 presidential contest. Former vice president Joe Biden, the presumptive Democratic nominee, leads President Trump by 15 points, according to its interviews. It was the largest advantage Biden has seen in the university’s polling, and it continued the trend of double-digit Biden leads in various polls.

“Yes, there’s still 16 weeks until Election Day,” Quinnipiac polling analyst Tim Malloy said in a statement, “but this is a very unpleasant real time look at what the future could be for President Trump.”

Trump’s reelection campaign, already on the defensive about its poor standing in the polls, immediately blasted the result.

“This poll is an absolute joke and Quinnipiac should be embarrassed to have it published,” the campaign’s communications director, Tim Murtaugh, wrote on Twitter. He picked a few arrows from the campaign’s quiver of responses to recent polling, focusing on how the parties were represented in the pool of respondents.

“The sample is D+10,” he pointed out — meaning the weighted percentage of respondents who were Democrats was 10 percentage points higher than the percentage who were Republicans. That’s true, as the poll’s methodology page makes clear: 34 percent Democrats, 24 percent Republicans and 34 percent independents.

Murtaugh’s point? Well, of course Biden is up by double digits when the number of Democrats being interviewed is 10 points higher than the number of Republicans. Therefore the poll should be dismissed out of hand.

There’s just one immediate problem with that argument: What if the density of Democrats in the country is 10 percentage points larger than the density of Republicans? What, in other words, if the problem for Trump isn’t that Quinnipiac included too many Democrats in the mix but, instead, that there are far more Democrats in the population?

A few hours after Murtaugh’s tweet, new data revealed that this is very much part of Trump’s problem.

We think of the electorate as polarized on party lines. Half Democrat, half Republican; a stalemate. But in reality, that’s not what things look like. The most common political identity in the United States is independent, as polling from Gallup over the years makes clear.

The most recent weekly data released by Gallup, from early June, shows a split that doesn’t match Quinnipiac’s weighting. About 31 percent of the country identifies as Democratic, compared with 25 percent who identify as Republican — a six-point gap. Forty percent identify as independent.

But among those independents, most (four-fifths) tend to align with one party. Most independents, in other words, are partisans who stand outside the party. And when you consider those leaners, the gap between the parties grows sharper.

According to Gallup, there’s an 11-point gap between the number of Democrats and Democrat-leaning independents and the number of Republicans and Republican-leaning independents — a large increase since earlier in the year. Such double-digit gaps are uncommon, Gallup’s Jeffrey Jones notes, seen only briefly during Barack Obama’s first term in office and during George W. Bush’s low points in his second term.

“Democrats appear to be as strong politically now as they were in 2018 when they reclaimed the majority in the House of Representatives and gained seven governorships they previously did not hold,” Jones writes. “If the strong current Democratic positioning holds through Election Day, Democrats could build off those 2018 successes to possibly win the presidency and Senate in 2020.”

In other words, this sort of preference for Democrats is the sort of thing that could lead to a very bad Election Day for such Republicans as the incumbent president. While Quinnipiac’s partisan distribution doesn’t perfectly overlap with the partisan identity measured by Gallup, it does reflect a broad preference among voters for the Democratic Party. A double-digit preference, even.

That this swing occurred largely from May to June suggests a level of volatility that could be seen as a point of hope for Trump’s campaign. It’s been a turbulent time and, should things settle a bit, it seems likely that there might be something of a reversion to norm.

But that doesn’t mean that Quinnipiac’s survey of the environment at this moment is incorrect because it reflects a broad preference for Democrats. According to Gallup’s data, it actually means that it’s correct.