George Santos on Thursday tweeted an angry denial that he competed as a drag queen in Brazilian beauty pageants 15 years ago, claims made by acquaintances that have highlighted the contrast between the Republican congressman’s past actions and now staunchly conservative views.

The New Yorker, who says he is gay, dismissed the story as an “obsession” by the media, which he insisted, without irony, “continues to make outrageous claims about my life”.

Santos is facing calls from Democrats and his fellow New York Republicans to step down over fabrications about his career and history and amid reports of investigations at local, state and federal level in the US and in Brazil over the use of a stolen checkbook.

In another contradiction exposed on Wednesday by a New York Times analysis of immigration records, Santos’s insistence that his mother was in the World Trade Center during the 9/11 terrorist attacks was found to be false.

Santos has admitted “embellishing” his résumé but otherwise denied wrongdoing and said he will not resign.

The claim that Santos was a drag performer came from a 58-year-old Brazilian who uses the drag name Eula Rochard, Reuters reported.

Rochard said she befriended Santos when he was cross-dressing in 2005 at the first Pride parade in Niterói, a suburb of Rio de Janeiro. Three years later, Santos competed in a drag beauty pageant in Rio, she added.

Another person from Niterói who knew Santos, but asked not to be named, said he participated in drag queen beauty pageants under the name Kitara Ravache, and aspired to be Miss Gay Rio de Janeiro.

Santos is now a hardline conservative on numerous social issues, especially those targeting non-binary communities. Republicans have taken aim at drag shows and performers in several states, claiming they are harmful to children.

In Texas, one proposal would brand venues that host such shows as “sexually oriented” businesses.

Santos, the first out gay Republican to win a House seat in Congress as a non-incumbent, has supported Florida’s “don’t say gay” law, which marginalizes the LGBTQ+ community and prohibits discussion of sexual orientation and gender identity in classrooms.

Responding in October to criticism of his support for the Florida bill, Santos told USA Today: “I am openly gay, have never had an issue with my sexual identity in the past decade, and I can tell you and assure you, I will always be an advocate for LGBTQ+ folks.”

Republican leaders have so far stood by Santos. He supported the new speaker, Kevin McCarthy, through 15 rounds of voting for that position, and was rewarded with seats on two House committees in a slim Republican majority.

But despite McCarthy’s support, increasing numbers of senior party officials have pleaded with Republican leadership to cut him loose. They include several of Santos’s fellow New York congressmen.

The Daily Beast reported on Thursday that a “shadow” race was under way in Democratic and Republican circles to replace Santos in New York’s third district, in the expectation that he will eventually be forced out. Republicans, the Beast said, are looking for “a candidate with an immaculate, bulletproof résumé who can patch up the Long Island GOP’s scarred reputation”.

Democrats are seeking somebody who can turn the district blue again after Santos’s surprise win in November.

As for Santos’s alleged drag show exploits, Rochard said the congressman was a “poor” drag queen in 2005, with a simple black dress, but in 2008 “he came back to Niterói with a lot of money” and a flamboyant pink dress to show for it.

Santos competed in a drag beauty pageant that year but lost, Rochard said, adding: “He’s changed a lot but he was always a liar. He was always such a dreamer.”

Santos’s tweet on Thursday was his second denial in two days concerning a claim about his past. On Wednesday, he was embroiled in allegations he took money from an online fundraiser intended to help save the life of a sick dog owned by a military veteran.

“The media continues to make outrageous claims about my life while I am working to deliver results,” Santos said. “I will not be distracted or fazed by this.”

On Thursday, Santos called “reports that I would let a dog die … shocking and insane”.

But the veteran told CNN Santos should “go to hell”.

Richard Osthoff added that if he spoke to Santos now, he would ask: “Do you have a heart? Do you have a soul?’

“He’d probably lie about that.”