I tend to take the pronouncements of former White House adviser Stephen K. Bannon with a bit of skepticism, so when he was quoted in July as declaring that “the Republican college-educated woman is done,” that white women with college degrees were giving up on the party, I figured I’d see whether that was the case.

It was the case. At that point, I made a version of the graph below, using every available Washington Post poll (with our partners at ABC News and the Schar School) for each election cycle. After 2016, the gap on the generic congressional ballot between support for Republicans and Democrats among white women with college degrees became a canyon. Including our most recent poll, the gap is 38 points — slightly narrower than in our last poll but still reinforcing the idea that the group isn’t going to be a bulwark of support for Republicans in November.

That gap is wider than among women overall, where Democrats have a 25-point margin. That’s because white women without college degrees still prefer Republicans to Democrats.

This is, in part, President Trump’s fault.

The split between white women with and without degrees has grown a lot wider since Trump took office. Using the most recent Post-ABC poll, we compared approval ratings among various groups at this point with where they stood in April 2017, the first point at which The Post and ABC polled on approval for Trump.

Here’s the overview.

Notice that white women with degrees had much bigger shifts since April 2017 than did white women without degrees. In April 2017, those without degrees were 11 points more likely to approve of Trump than those with degrees. Now the gap is 26 points, mostly a function of the sharp drop in approval among those with degrees.

At the same time, the percentage of white women with college degrees who view Trump negatively has risen. But notice, too, the numbers for white men without college degrees. In our most recent poll, the percentage of that group that disapproves of Trump has increased by 14 points since April 2017. This is significant because the group was one of the key factors in Trump’s 2016 victory and has consistently been considered a core part of his base.

Among white men without college degrees who identify as evangelical Protestants, Trump fares better: 69 percent approve of him, 46 percent of them strongly. Only 55 percent of white men without degrees overall approve of Trump — down 10 points since April 2017. Remarkably, nearly 4 in 10 in that group strongly disapprove of Trump’s job performance, a 15-point increase since our first poll.

This poll could be an anomaly. It continues to be the case that Trump’s overall approval rating across multiple polls has been fairly static, generally hovering at or around 40 percent. (In our new poll, his overall approval rating was 36 percent, six percentage points lower than in April 2017.)

But that anomaly comes at an inconvenient time for a president who is increasingly showing signs that he’s worried about the November elections. We’ve noted before that there’s a correlation between how Republicans fare on the generic ballot and how Americans view Trump. As Trump’s approval drops, the net advantage for Democrats on the generic ballot has generally increased.

White, college-educated women still look as if they’re going to overwhelmingly back Democrats in November. In the chart at the top of this article, though, notice the graph at the far left: White men without college degrees are much more likely to back Democrats now than they were in The Post’s other recent polls — in fact, than in any Post poll in almost a decade.

If that holds — in the president’s putative base! — November 2018 could be particularly grim for Trump. To say nothing of November 2020.