The Post-ABC News poll taken Aug. 26 to 29 might send some tremors through the GOP. President Trump’s approval rating is down to 36 percent, matching his all-time low, and his 60 percent disapproval rating is at an all-time high. (Among registered voters, his approval rating is a smidgen higher at 38 percent.) Worse still, his approval rating among Republicans is now below 80 percent, and his support among white voters is down to 45 percent, with 51 percent who disapprove. His gender gap is enormous: 54 percent of men disapprove of his performance, while 66 percent of women do. Among independents, 59 percent disapprove of his performance.

We don’t know whether this is simply the “noise” of minor poll blips or whether the confluence of events — Paul Manafort’s conviction, Michael Cohen’s plea deal, Trump’s boorish behavior regarding the passing of national hero Sen. John McCain (R-Ariz.) — or something else altogether has eaten away at his support.

Even on the economy, he is slightly underwater (45 percent approve, 47 percent disapprove). Certainly, the upcoming midterms have excited voters, with 65 percent saying they think it’s more important than usual to vote, 31 percent saying they feel about the same, and a mere 3 percent who say it is less important. That might be a bad thing indeed for Trump, if voters are itching to express their displeasure with him.

As for the issue of corruption, a 45 percent plurality think it has gotten worse under Trump, 39 percent say it’s about the same, and only 13 percent say it has decreased. The man who was elected to drain the swamp has managed to convince voters that it is the same or worse.

Trump likes to say he keeps his promises. But his vow to drain the swamp might be one of the most egregious broken pledges in recent history. Trump built his campaign around “Crooked Hillary,” and then launched an administration second to none in conflicts of interest, self-dealing, and convictions and plea deals by former officials and campaign aides.

Voters seem foursquare behind the Russia investigation (63 percent approve, while only 29 percent disapprove); 53 percent say that he has interfered with the investigation to such an extent that it amounts to obstruction of justice, while only 35 percent do not. A majority of Republicans still oppose the investigation and insist that Trump hasn’t interfered with the special counsel’s work.

As Congress abdicates its role, columnist E.J. Dionne Jr. says voters must take up the role of checking President Trump. (Adriana Usero/The Washington Post)

As for Manafort, 67 percent (including a plurality of 48 percent of Republicans) think his conviction was justified, while only 17 percent do not. By a similar margin (66/18) voters, including a plurality (45 percent of Republicans), disfavor giving him a pardon. Asked to choose sides between Trump and Attorney General Jeff Sessions, 62 percent pick Sessions and only 23 percent pick Trump. Americans also strongly oppose firing Sessions (64/19), including a strong plurality of Republicans (47/31).

When it comes to former Trump personal lawyer Michael Cohen, there is more bad news for Trump. If he directed Cohen to commit a crime, 61 percent think Trump must have committed one, too.

Finally, a slim plurality (49 percent to 46 percent) already think Congress should commence impeachment hearings.

Understand, of course, that this is one poll and that the shift in Trump’s numbers are generally within the margin of error. However, if duplicated elsewhere and over some period of time, it’s worth reexamining the assumption that Republicans will stick with Trump. We might have to consider that he might actually be afraid to fire Sessions and to pardon Manafort for fear of the consequences. If voters are souring on Trump and take it out on Republicans in November, it’s very possible that his efforts to curtail the Russia investigation, including by firing Justice Department supervisors or pardoning cronies, will be enough to push a lot of voters over the edge.

Republican candidates who have tied themselves tightly to Trump this year, reveling in endorsements, might find that the association with Trump hurts more than it helps. And if that’s the case and Democrats roll up big gains knocking out Trump acolytes, you might just see some 2020 GOP challengers step forward. There is nothing like an election wipeout to shatter a cultist politician’s support.