A leading congressional Republican is now warning that federal prosecutors are not looking at the broader picture of potential misconduct by Hunter Biden and his family, and that witnesses in the GOP investigation, as well as investigators themselves, are being threatened and terrorized by powerful Democrats.

The chairman of the House Oversight Committee, Congressman James Comer, told the television program “Just the News” that he is concerned about alleged threats made against witnesses from Mr. Biden’s financial institutions, as well as about threats made against members of Congress who are investigating alleged corruption and crimes by the Biden family. 

“We’ve got witnesses that are scared to death to come forward,” Mr. Comer said on Friday. “They fear for their lives. I mean, you’ve got the banks that have worked with us, they’re being squeezed by attorneys, by high-ranking officials in the Democrat Party for having the nerve to work with us to comply with our subpoenas.”

Mr. Comer also said that “dark money” groups have been cutting checks to intimidate members of Congress. “I’ll put it like that with respect to witness intimidation. I mean just look in my district. We’ve got dark money groups that are being funded through prominent high-ranking Democrat officials in Congress. Also the communications director for the White House continues to retweet things trying to intimidate me.”

Concerns have recently arisen over the criminal investigation being conducted by the Department of Justice, as well as a whistleblower report from an agent at the Internal Revenue Service. The United States attorney for the district of Delaware who was appointed by President Trump, David Weiss, is investigating whether Mr. Biden evaded taxes and lied about drug abuse in order to obtain a firearm. The DOJ has been accused, including by an anonymous IRS supervisor turned whistleblower, of slow-walking the investigation and hampering Mr. Weiss. 

In a letter provided to the Wall Street Journal, the anonymous supervisory agent at the IRS claims the agency’s investigation into tax evasion by Mr. Biden is being mishandled. The letter states that there has been a “failure to mitigate clear conflicts of interest in the ultimate disposition of the case.”

Hunter Biden’s legal team recently launched an aggressive public relations campaign that called on the Office of Congressional Ethics to sanction Congresswoman Marjorie Taylor Greene for her criticism of the president’s son.

It’s one of the younger Mr. Biden’s first public responses to congressional Republicans’ investigation into his tangled business practices and ties to foreign governments.

In a letter obtained by Politico, Mr. Biden’s attorney, Abbe Lowell, said Ms. Greene’s online criticism of his client is a violation of congressional ethics rules. “Representative Greene’s unethical conduct arises from her continuous verbal attacks, defamatory statements, publication of personal photos and data, and promotion of conspiracy theories about and against Robert Hunter Biden,” Mr. Lowell wrote. 

The letter states that Ms. Greene’s public persona does not “reflect the credibility of the House” as defined in an ethics rule written in the late 1960s. Mr. Lowell points out that another GOP congressman, Matt Gaetz, was admonished by the House Ethics Committee, under the same rule he now invokes, in 2020 for a social media post that was read to be a threat of retaliation against President Trump’s former personal attorney, Michael Cohen. 

Mr. Lowell provided links to multiple social media posts from Ms. Greene in recent months about Hunter Biden, including when she posted a photo of Mr. Biden and one of his daughters, referring to the young girl as a “prostitute.”

Ms. Greene took to Twitter on Monday to respond to the letter. “Hunter is upset over my statements,” the Georgia congresswoman wrote. “Well Hunter, the entire country is pissed off about your obvious influence peddling with your Daddy’s political power. Come chat with us Republicans on the Oversight Committee. We have a lot of questions.”

The oversight committee recently claimed that Mr. Biden was involved in a payment scheme that funneled money from a Chinese Communist Party-backed company to his late brother’s widow, who also dated Mr. Biden after Beau Biden’s passing. 

Mr. Comer says that over the course of three months in 2017, the Biden family collectively received more than $1 million in payments from a business associate of Hunter’s who worked with him in the Chinese energy market, Rob Walker. 

Of that money, Beau Biden’s widow, Hallie Biden, received two payments totaling $35,000 from Mr. Walker’s limited liability companies that the GOP committee says were paid by a Chinese energy company, State Energy HK Limited. It is unclear what business services she provided to receive the money. Hallie Biden used to work as a school counselor, but now sits on the board of the Beau Biden Foundation. 

The committee says Hallie Biden is “a new person of interest in the Biden Business Scheme.”

“The Oversight Committee is concerned about the national security implications resulting from President Biden’s family receiving millions of dollars from foreign nationals. We will continue to follow the money trail and facts,” the committee said in a statement.