Speaking briefly to reporters on Capitol Hill, President Trump on Tuesday revisited a theory that he has offered before: The investigation into his 2016 campaign and possible links to Russia was initiated at the behest of Barack Obama.

“You’re accusing the people who launched the investigation into your campaign of treasonous acts,” a reporter said to Trump.

"Yeah,” Trump replied.

"How high up do you think it went?” the reporter asked.

"I think it went very high up,” Trump said, then calling the investigation a “disgrace."

“It went very high up,” Trump continued, “and it started fairly low but with instructions from the high up. This should never happen to a president again. We can’t allow that to take place.”

"Do you think it reached the West Wing of the Obama White House?” the reporter asked.

“I don’t want to say that,” Trump replied, “but I think you know the answer.”

We’ll note quickly that the assertion that there is, by definition, no conceivable way in which any even theoretically actions taken against Trump were treasonous. The more important assertion made by Trump is that Obama or his top aides were the ones pushing for an investigation, offering “instructions from ... high up.”

Trump has made similar allegations in the past. Speaking to Fox News’s Sean Hannity last July while in Helsinki for a summit with Russian President Vladimir Putin, Trump was more direct.

Obama “thought that Hillary Clinton was going to win,” Trump said, “he didn’t want to do anything to disturb it, and you know, frankly, when I won, he said: This is the biggest deal. But I won, he said this is nothing, and it can’t happen. It’s a very dishonest deal. And you know, you have to find out who did Peter Strzok report to? Because it was Comey and it was McCabe, but it was also probably Obama. If you think that Obama didn’t know what was going — ” He then started another thought.

There are few things that President Trump won't blame former president Barack Obama for. (Monica Akhtar/The Washington Post)

Strzok is the former FBI agent who launched the initial investigation into possible collusion between Trump’s campaign and Russia in late July 2016. He worked for then-FBI Deputy Director Andrew McCabe and then-FBI Director James B. Comey. All three have since resigned or been fired from the bureau.

Trump’s point, though, is again that someone lower-level — Strzok, in this case — was working at the behest of Obama.

(Hannity, whose show Trump watches regularly, similarly implied a higher-level effort during his program on Monday: “People with the highest levels of power abused that power to exonerate one candidate that we know should have been indicted, and to rig a presidential election, and then undo the results that they didn’t like,” he said. “You — we, the American people — were lied to over and over and over again.”)

Trump first alleged that Obama was involved in investigating him in March 2017, less than two months after his inauguration. That was when he infamously accused Obama of wiretapping the phones in Trump Tower after reading a sketchy Breitbart article picking up an allegation from right-wing radio host Mark Levin. That allegation was repeatedly rejected by Trump’s own national security staff.

Shortly after that, Rep. Devin Nunes (R-Calif.) tried to bolster a broader interpretation of Trump’s claim — that Trump’s team broadly was surveilled — by revealing that Obama administration officials had sought to identify Americans who were speaking with overseas individuals. That included former national security adviser Michael Flynn, who later admitted lying to the FBI about his conversations with Russian Ambassador Sergey Kislyak.

Soon, though, Trump’s focus on the genesis of the investigations into him became Strzok and his texts with former FBI lawyer Lisa Page. Those texts, in which the pair disparage Trump and make questionable comments about his candidacy, became the centerpiece of theories about how the investigations into Trump were built on prejudice, not facts.

In February 2018, Trump hailed one set of texts as “bombshells.” Included among them was a message from Page to Strzok in September 2016 where she writes that “potus wants to know everything we are doing.” This was interpreted as suggesting that Obama was intimately involved in the investigation into Trump’s campaign, but Strzok and Page told investigators that it was more broadly about the investigation into Russia’s attempts to influence the 2016 election. (This is bolstered by the fact that Obama a few days later met with Putin personally and challenged him on Russia’s 2016 activity.)

There is not evidence, in fact, that points concretely to Obama having any role in the genesis of the investigation into Trump’s campaign. Perhaps Trump has seen some. Or perhaps he’s making an unfounded insinuation.

Why would he make such an insinuation? For several possible reasons.

One possibility is that Trump believes it. He’s no stranger to promoting questionable conspiracy theories, and he’s clearly not a fan of his predecessor. It seems safe to assume that, at least on some level, Trump thinks that Obama might actively have worked against him, even if it meant bending the rules.

Another possible reason is that by pinning the investigation on Obama, an unambiguously political actor, Trump suggests that the investigation was broadly initiated for political reasons. It’s tricky (though not impossible) to claim that Comey (a lifelong Republican) allowed the investigation to move forward for political reasons or that Deputy Attorney General Rod J. Rosenstein (a Trump appointee) named special counsel Robert S. Mueller III out of a sense of bias. It’s much easier to ascribe partisan motivations to Obama, who, during late 2016, was actively campaigning against Trump.

Trump has done a remarkable job of convincing Republicans that the investigation was an unwarranted effort to railroad him. (A newly released Quinnipiac University poll finds that 83 percent of Republicans believe the investigation was “a political witch hunt.”) But it’s useful, with 2020 looming, for Trump to link that effort to Democrats than to the “deep state.”

Some random guy named Peter Strzok trying to take down Trump is one thing. President Obama trying to take down Trump? That’s the sort of thing that might inspire people to go vote Republican.

Even if there’s no evidence that it’s true.