To hear President Trump tell it, the Democrats’ push for an impeachment inquiry is nothing but a boon for him, politically.

“This is a scam, and the people are wise to it,” Trump said at an event on Monday. “And that’s why my polls went up — I think they said — 17 points in the last two or three days. I’ve never had that one. I’ve never had that one."

Of course, Trump says things that aren’t true all the time. And this isn’t true, either.

Trump appears to be referring to a poll from Investor’s Business Daily and TIPP that showed Trump improving 17 points — with four important caveats. First, this wasn’t a change over “two or three days,” but instead over the past month. Polls don’t shift 17 points in a few days outside a massive news event, and last weekend doesn’t count in that regard. Second, the shift was only among independents, meaning a smaller group with a larger margin of error. Third, it was a shift in margin, not support; Trump’s position improved only 8 points. And fourth, the IBD/TIPP poll is only one poll.

There is another new poll worth considering here: A Washington Post-Schar School poll released Tuesday morning. Our poll paints a much bleaker picture for Trump overall — but also suggests that the administration’s scramble to rationalize Trump’s behavior is not gaining any substantial traction at all.

The last time The Post polled on the question was in July. Since then, there’s been a big increase in support for the House launching an impeachment inquiry: 20-point increases across party lines.

What’s more, there’s been a decrease in opposition to an inquiry — including a 17-point drop overall of those who strongly oppose launching an inquiry. The drop among Republicans was 24 points. In July, 83 percent of Trump’s party strongly opposed an inquiry. In our new poll, that figure is only 59 percent.

Since news of Trump’s efforts to cajole Ukraine’s president into conducting politically useful investigations broke last month, Trump and his allies have been scrambling to brush the controversy away. They’ve deployed a see-what-sticks approach that, so far, hasn’t resulted in anything really sticking as a defense beyond “what Trump did is okay, full stop.”

Our poll asked that question specifically: Was Trump’s request to Ukrainian President Volodymyr Zelensky to investigate Biden appropriate? Only a third of respondents said it was — and a third of Republicans said it wasn’t.

Sure, more than half of Republicans said that what Trump did was appropriate, but Republicans are the only group that has stood with Trump consistently over the course of his presidency. That a third are now skeptical of the actions at the heart of the impeachment inquiry, joining robust majorities of Democrats and independents, is significant.

If this figure (which, of course, is just one poll) holds, the significance is probably greater than it seems. Over the course of his presidency, Trump has demonstrated an ability to generate rationales for even his most controversial behavior, quickly landing on excuses that his core base of support can use to fend off criticism. On Ukraine, that ability is faltering.

Perhaps it’s because new revelations are coming in a deluge, making it hard to land on one overarching rationalization. What’s more, new revelations have washed away rationales already presented by the White House. (The dismissal among Trump’s allies that the intelligence-community whistleblower was relying on hearsay, for example, was undercut entirely by the release of a rough transcript of the Trump-Zelensky call showing that the whistleblower nailed the contents of the call.) Or perhaps it’s because the question at hand — was the behavior appropriate? — is both straightforward and hard to defend on the merits.

Particularly in the broader context of Trump’s efforts to pressure Ukraine. A third of Republicans, for example, think that the Trump administration’s still-unexplained decision to halt aid to Ukraine is an important consideration in evaluating Trump’s request. There’s really only one way to read that: A third of Republicans think it’s possible that Trump was using American aid as leverage.

More than half of respondents agree.

It’s important to note that our poll also showed that three-quarters of Republicans think that Democrats are overreacting on the Ukraine issue. A bit under a quarter of Republicans thought they weren’t, a figure a bit under the percentage of Republicans who support the inquiry.

Again, though: In this hyperpartisan moment, about a fifth of Trump’s own party thinks that their political opponents aren’t overreacting in pressing for an impeachment inquiry centered on Trump’s request to Ukraine’s president.

Trump might yet develop a rationale for his actions that brings his party back on board. For the moment, though, the Ukraine question appears to be sticking.