Donald Trump’s presidential campaign is in deep, deep trouble.

A new poll from NBC News and the Wall Street Journal — conducted after Trump’s leaked tape scandal broke but before Sunday night’s debate — finds that Clinton leads Trump by 11 points nationally in a four-way matchup including Gary Johnson and Jill Stein, and by 14 points in a head-to-head two-way matchup.

Now, keep in mind that this poll is still an outlier in the context of the evidence we have. It’s best not to overinterpret results of individual polls, and to focus instead on averages of multiple polls.

But it’s noteworthy that this is Clinton’s largest lead in a major poll since August, and if that were the actual margin on Election Day, it would be the biggest national landslide in a presidential race in decades.

It is also a lead big enough to easily give Democrats control of the Senate, and perhaps sweep them back into power in the House of Representatives too. Indeed, the poll also shows Democrats with a 7-point lead on the generic congressional ballot.

This new poll result corroborates rumors that Republican operatives have been seeing dismal numbers for Trump in their private polling since the tape revelation. One House leadership aide told Jon Ward of Yahoo News that the House was in play and that that judgment was based on data (though “more will need to come in over the next few days to be certain,” Ward wrote).

The other evidence from less established polls we’ve gotten so far has also varied from mediocre for Trump (Morning Consult showed him losing only a point of support) to disastrous (Rasmussen showed him going from down 1 point to down 7 points since Friday).

Now, Trump’s numbers in the NBC/WSJ poll could have been depressed somewhat by differential non-response — his weekend from hell could have made his voters simply temporarily less likely to pick up the phone, and they could regain their enthusiasm in the coming days.

And note that this poll was taken before Sunday night’s debate, so it’s at least conceivable that Trump could have helped stanch the bleeding a bit with that performance. But early polls indicate that more voters thought Clinton won the debate, so he seems unlikely to have been helped all that much.

Still, while it is surely possible that Trump will regain some ground, it’s also possible that his standing could collapse even further, particularly if leading Republicans continue to defect from his cause, or if more damaging revelations about his past emerge.

This could send his campaign — and Republicans’ prospects more generally — into a self-perpetuating death spiral, as bad news piles atop bad news, driving swing voters away from Trump and making Republican partisans less likely to bother to turn out on Election Day.

Watch: Democrats are in trouble even if Clinton wins