Hillary Clinton speaks at an LGBT for Hillary Gala at the Cipriani Club in New York on Sept. 9. (Andrew Harnik/AP)

After its national poll in late August, the pollsters at Quinnipiac University offered surprising context for their findings. "We are starting to hear the faint rumblings of a Hillary Clinton landslide," they wrote. As it turns out, their ears may have been not to the ground but instead to the railroad tracks, where the Trump train was merrily making its way forward.

Democrats who a month ago were measuring the curtains in the Oval Office, and even the House speaker's, are — after a new Quinnipiac poll released Wednesday and polls from CNN-ORC and Bloomberg showing Trump with leads in Ohio and Florida — now Googling to see just how much rent they'd have to shell out for an apartment in Toronto. Quinnipiac still has Clinton up by 5 nationally, in line with the recent Washington Post-ABC poll, but that's a sharp dip from two weeks ago. Polling is all about trends — photos of the horses in a horse race — and what these polls suggest is that Trump is gaining in the back stretch.

Of course, those Democrats (and some never-Trumpers, I'm sure) should probably hold off on sending in deposits, for reasons I outlined this morning. Donald Trump needs to win 116 electoral votes in the 10 states that are within 5 points in RealClearPolitics' average right now. Clinton only needs to win 14. That said, FiveThirtyEight's Nate Silver notes that state polls will follow the national ones, so there's no guarantee such a sweep is out of the picture — or that other states won't join the list of those that are close.

One thing that the new Quinnipiac and CNN-ORC polls should suggest to us, though, is that Clinton's expected base of support — like so many Democratic candidates before her — is likely more fragile than Trump's. But unlike past Democrats, her base is unusually fragile.

The Atlantic's Ron Brownstein pointed to an interesting detail in that Quinnipiac poll. Here's how support for Trump and Clinton changes when you add the Green Party's Jill Stein and Libertarian Gary Johnson to the mix.

(The Washington Post)

Compare the red and blue bars. Among those 35 and older, the red and blue bars fall by about the same amount when going from a two-way to four-way contest. But not among those 34 and younger. That blue bar drops far more than the red one.

We can quantify that change. It happened in the August "drumbeat" poll, too, with Clinton losing 16 points when the question included all four candidates and Trump losing only 5. In the poll, Clinton loses 24 points of support to Trump's 8. She's essentially tied with Trump and Johnson with that group.

(The Washington Post)

President Obama got 60 percent of the vote of those ages 18 to 29 in 2012 and 66 percent in 2008. Clinton's at only 31 percent in that four-way contest. In 2004, John F. Kerry won young voters by only 9 percentage points, on his way to losing the election.

Identifying a cause isn't too tricky: Why might younger voters prefer an independent candidate (when available) to Clinton? For whatever reason they did so by massive margins in the Democratic primary.

The CNN-ORC Ohio poll reveals another challenge for Clinton in new polls. As with the CNN-ORC national poll that came out last week, the pollsters have moved to a likely voter pool, meaning that instead of focusing on registered voters, who may or may not actually vote, the focus is on voters who plan to get to the polls. That's a shift that often favors Republicans, because age, income and homeownership all correlate to likelihood to vote. Those indicators also overlap more heavily with white voters.

Quinnipiac used a likely voter pool in August and its new survey. But there are other important slides for Clinton in Quinnipiac's poll. Up 21 with women in August, she now leads by only 12. She's gone from trailing by 1 percentage point among independents to trailing by 9. Among nonwhite voters, Clinton has gone from a 56-point lead to a lead of 39 points.

The picture of the past month of the campaign is an easy one to describe: It's getting closer. Remember when Trump was trailing because people were afraid of admitting their support for him to pollsters? Apparently they've stopped doing that.

(The Washington Post)

Clinton's position has softened, and, on the day we learn that Johnson will be on the ballot in all 50 states, we see a way in which that could make her support softer still.

The rumblings have gone quiet.