Standing before a crowd of supporters this week in Lexington, Ky., President Trump repeated a false claim he has made more than 100 times in the past six weeks: that a whistleblower from the intelligence community misrepresented a presidential phone call at the center of the impeachment inquiry that threatens his presidency.

‘‘The whistleblower said lots of things that weren’t so good, folks. You’re going to find out,’’ Trump said Monday at a campaign rally. ‘‘These are very dishonest people.’’

Behind him were men and women in ‘‘Read the Transcript’’ T-shirts — echoing through their apparel Trump’s attempt to recast an incriminating summary of his July 25 call with Ukraine’s president as a piece of exonerating evidence.

It’s a form of gaslighting that has become the central defense strategy for the president as he faces his greatest political threat yet. But the approach is coming under increasing strain as congressional Democrats release transcripts and prepare to hold public hearings presenting evidence that directly undercuts Trump’s claims.

That the whistleblower report essentially mirrors the set of facts that have since been revealed by a stream of documented evidence and sworn testimony has not stopped Trump from repeatedly claiming otherwise. He has also pushed other specious arguments in his harried attempt to counter the growing evidence from witnesses implicating his administration in a quid pro quo scheme linking military aid to Ukrainian investigations targeting Democrats.

Without evidence, Trump has claimed that his own administration officials who have complied with congressional subpoenas are ‘‘Never Trumpers.’’ He has recounted conversations in which senators deemed him innocent, only to have the lawmakers deny making the statements. He has dismissed polls that show growing support for impeachment as fake, while repeatedly claiming levels of Republican support that exceed anything that exists in public polling.

‘‘I don’t know whether he believes all these things or he takes pleasure in inventing false narratives, but I think the most important thing here is that no president can sustain his hold on the public for long when he loses his credibility,’’ said Robert Dallek, a presidential historian.

The White House did not respond to requests for comment.

Since Democrats began their impeachment inquiry in September, Trump’s most consistent defense has been the false assertion that the whistleblower complaint ‘‘bears no resemblance’’ to his July 25 phone call with Ukrainian president Volodymyr Zelensky. Trump has referred to the whistleblower’s allegations as ‘‘false,’’ ‘‘fraudulent,’’ ‘‘wrong,’’ ‘‘incorrect,’’ ‘‘so bad,’’ ‘‘very inaccurate,’’ and ‘‘phony.’’

But the whistleblower’s account — which documented how Trump pressed Zelensky to work with Attorney General William Barr and Trump’s personal lawyer Rudy Giuliani to investigate former vice president Joe Biden and his son Hunter — has been corroborated by the reconstructed transcript released by the White House. Witness testimony has also backed up most of the whistleblower report’s main conclusions, including that White House lawyers sought to ‘‘lock down’’ records of the call by moving it onto a highly classified system.

Trump’s willingness to repeatedly mislead the public represents an attempt to protect himself by creating doubt about the fundamental nature of truth, said Michael Steele, former chairman of the Republican National Committee.

‘‘One thing we’ve all noticed with Trump is he knows how to strategically create confusion,’’ he said. ‘‘To go on the record with a bold-faced lie. It doesn’t matter whether you fact-check him in real time, it doesn’t matter if there’s a human cry afterwards, his calculation is that there’s enough confusion that you don’t know what’s true and what isn’t.’’