For much of 2015, Donald Trump’s standing primary stump speech included quite a few references to public-opinion polls. The New York Republican saw all the surveys showing him dominating GOP polls for months, and he was eager to tout his advantage on a daily basis.

That bravado, like his polling edge, is long gone. Though national surveys showed Trump neck and neck with Hillary Clinton a month ago – some polls even showed him inching ahead – the Republican’s recent antics have pushed his support to depths unseen in quite a while.

On Friday, Trump was reduced to tweeting about a dubious national poll – which showed him losing . (As a rule, presidential candidates don’t brag about survey results in which they’re behind.)

The New York Times, which noted that Trump “rarely, if ever, acknowledges he might be losing at anything,” reported that the candidate conceded late last week that he’s not, at present, winning.

“I’m four down in one poll, three and a half in another that just came out, and I haven’t started yet,” Mr. Trump, the presumptive Republican presidential nominee, said in a phone interview on Thursday night, a thought he volunteered as he dismissed concerns from Senate Republicans that he may be a drag on their candidacies in the fall. “And I have tremendous Republican support,” Mr. Trump said.

And if the race for the presidency was limited to Republican voters, that might be a relevant observation.

As for the assertion that Trump hasn’t “started yet,” he’s now been running for president for a full year, and he wrapped up the GOP nomination in early May. I’m reasonably certain he has “started,” but if he hasn’t, perhaps Trump might want to explain exactly what he’s waiting for.

Over the weekend, Trump added that the latest polling shows he’s “ essentially even ” with Clinton, which is true if you define “even” as “not particularly close.” In fact, the Washington Post reported over the weekend, “ Not only are Trump’s poll numbers slipping, they are at a low that no one, Republican or Democrat, has seen in the past three election cycles…. T he margin by which he trails Hillary Clinton now mirrors McCain’s deficit to Barack Obama in 2008. McCain rebounded after the Republican convention — but it’s important to remember that we’re comparing Trump to the worst Republican performance in a general election since 1996.”

But perhaps most interesting of all was something Trump told an audience in Denver.

“When I poll, I do fine, but when I run I do much better,” Trump told supporters. “In other words, people say I’m not going to say who I’m voting for, don’t be embarrassed, I’m not going to say who I’m voting for and then they get it and I do much better, it’s like an amazing effect.”

It’s unclear if Trump knows what he’s saying, but this is actually a provocative point. Some political observers believe in something called the “Bradley effect,” and Trump evidently believes it’s in effect right now, skewing the poll results.

In case anyone needs a refresher , in California’s 1982 gubernatorial campaign, polls showed then-Los Angeles Mayor Tom Bradley (D) comfortably ahead in the statewide race. The polls, however, were wrong – and Bradley lost in a very close contest.

Some social scientists argued soon after that the pre-election data were off for a very specific reason: voters lied to pollsters about their intentions towards Bradley, an African American, who ran against a white rival. The “Bradley effect” was born.

The Wikipedia description is as good as any: the theory “posits that the inaccurate polls were skewed by the phenomenon of social desirability bias. Specifically, some white voters give inaccurate polling responses for fear that, by stating their true preference, they will open themselves to criticism of racial motivation. Members of the public may feel under pressure to provide an answer that is deemed to be more publicly acceptable.”

The theory has plenty of critics, and some political scientists question its validity. Your mileage may vary.

Either way, it’s notable that Trump is apparently on board with the idea. We shouldn’t necessarily believe the polling, he’s arguing, because Americans who intend to vote for Trump are too embarrassed to admit it when asked for their preference in surveys. Once you account for the fact that Trump supporters feel a sense of shame, and don’t want to acknowledge their true beliefs to pollsters, maybe he’s doing far better than the data suggests.