An IRS whistleblower says the FBI's FD-1023 document that alleges a bribery scheme involving President Joe Biden, his son, Hunter, and a foreign national was never delivered to investigators, even though it was sent to the Delaware U.S. attorney for further investigation.

On Thursday, the House Ways and Means Committee released of portion of whistleblower testimony related to the IRS and Justice Department probe into Hunter Biden's "tax affairs." The federal probe began in 2018, amid the discovery of suspicious activity reports regarding funds from "China and other foreign nations."

That investigation originated out of the U.S. Attorney's Office in Delaware under U.S. Attorney David Weiss.

One whistleblower who spoke to House Republicans, Gary Shapley Jr., testified that decisions in the case seemed to be "influenced by politics," including those related to the FD-1023 document.

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A second whistleblower was unnamed but said he "initiated the criminal tax investigation" into Hunter Biden as a special agent with the Internal Revenue Service Criminal Investigation who worked under Shapley.

He also said, in a supplemental letter submitted to the committee from his lawyer, that he was never informed of or received the FD-1023 document that was reportedly sent to the Delaware U.S. Attorney's Office for investigation, and which may have been useful as Hunter Biden was being investigated.

Fox News Digital reported this month that the contents of the FD-1023 allege that Joe Biden was paid $5 million by an executive of the Ukrainian natural gas firm Burisma Holdings. Biden's son, Hunter, sat on the board of that company as part of an alleged bribery scheme that involved influence over U.S. policy decisions, according to sources familiar with the document.

"In news articles, former AG William Barr is cited in saying that this Form 1023 was reviewed by the Western District of Pennsylvania and was ultimately shared with David Weiss, U.S. Attorney overseeing the subject Investigation," the letter said.

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"As Mr. X has testified, he was the IRS-CI Case Agent over the subject investigation at the time – and Mr. X has stated to me that he has never seen this FBI Form 1023 and that he does not recall ever hearing about this information being turned over in any meetings with the prosecution team in Delaware," it said.

"Further, Mr. X informed me that this information could have been relevant to Mr. X’s investigation at the time of the subject as it related to a claim of $5 million being paid to the subject which directly ties to email correspondence reviewed between subject and a business partner of subject sent in May of 2014, which is believed to reference the $5 million…," the letter said.

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Barr previously told Fox News that during his tenure the FD-1023 document was reviewed by U.S. Attorney Scott Brady and his team in Pittsburgh as part of a screening process to determine the veracity or relevance of information.

Barr said there was "no sign" that the FD-1023 contained disinformation and was therefore routed to Trump-appointed U.S. Attorney Weiss in Delaware – who was and is still working a probe focusing on Hunter Biden.

The whistleblower, or "Mr. X" as he's referred to in the letter, testified that he considers himself to be a Democrat," identifies as a "career government employee."

"I've tried to stay so nonpolitical that in the last presidential election I voted but had decided to not vote for the presidential candidate because I didn't want to be asked that question in a court proceeding in the future, and I didn't want to show any potential bias," he testified.

Last week, Sen. Chuck Grassley, R-Iowa, who has been working in tandem with House Republicans in urging the release of the FD-1023, said from the Senate floor, "So, as I’ve repeatedly asked since going public with the existence of the 1023, what, if anything, has the Justice Department and FBI done to investigate?"

"The Justice Department and FBI must show their work," he said.

Barr also told Fox News Digital that current Attorney General Merrick Garland should release the FD-1023 form to Congress, providing necessary steps are taken to protect the life and safety of the confidential human source in the document.

As "Yellowstone" prepares to wrap up the hit show after five seasons, Lainey Wilson is just as excited as fans to see how the series will end. 

"I have realized that the TV world is even crazier than the music world," she said during an interview with People. 

"I'm like, ‘Taylor Sheridan, you got to let me know what's going on, bro.’ I'm excited to see what happens. There’s no doubt the rest of season five is gonna be money."

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While the second half of the fifth season of "Yellowstone" is expected to premiere in November, the country star admitted she’s also in the dark about co-creator Sheridan’s plans for the series. 

Wilson portrayed the singer Abby on the hit show "Yellowstone" for four episodes.

The 30-year-old artist pointed out how "Yellowstone" has made a major impact in the western world and the music industry overall. 

"What ‘Yellowstone’ has done for the western way of life has been a huge turning point," she said. "I feel like what I do was not cool three or four years ago."

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The "Atta Girl" crooner dished on her meeting with Sheridan when he asked her to become part of the series. 

"Taylor Sheridan called me and he said, ‘Lainey, I got this idea. I want you to play a musician, but I want you to pretty much be yourself and wear your bell-bottoms… sing your own music,’" she remarked. "It was a huge opportunity for me to share my music with the world."

Wilson additionally noted that she had reservations about signing onto the "Yellowstone" cast since she’s never acted before.

She reflected on the first time she met Kelly Reilly, who plays Beth Dutton on the show.

"I'm like, ‘I'm about to meet Beth – she's probably gonna put me in a headlock,’" Wilson laughed.

"But she didn't; she made me feel so welcome. She lifted me up, she encouraged me, she gave me some advice. My very first scene was with her, and she told me, ‘I would’ve never known this was your first time acting. If you had not told me, I would have thought you’d been doing this forever.’ Hearing things like that from Kelly made me feel like, ‘You know what? I can do this.’"

The "Heart Like a Truck" singer emotionally opened up about how her father suffered from a stroke and was hospitalized while she was filming the hit show. His illness caused him to have nine surgeries and his left eye removed. 

When Wilson had to make the decision if she was going to return to the "Yellowstone" set or be with her father at the hospital, she said he encouraged her to work after overhearing her phone conversation.

"He opened his eyes and said, ‘Did I hear that you're not going out to film 'Yellowstone'?’ I said, ‘Daddy, I can't leave you.’ He said, ‘You better go, and you better not come back until the job is done,’" she explained.

"That is the girl that he raised. So, I headed that way and did it. It’s that mentality right there that I feel has gotten me to this place."

During the Country Music Awards last year, Wilson was accompanied by her father on the red carpet after he recovered from his stroke. She told Fox News Digital at the time that it was "a dream."

Wilson also shared that her father used to roll out a picnic table on the side of the highway and "pretend" he was Glen Campbell, while playing for cars passing by.

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"He's getting to live vicariously through me, and I'm so glad and so thankful that he is around to see the things that are happening right now. He's real proud," she told People.

It was announced last month that the Kevin Costner-led "Yellowstone" will air the second half of its fifth and final season in November before rolling out an unnamed sequel series in December.

There is still no word on when the final episodes of "Yellowstone" will be filmed.