House Republicans are entering a critical phase of their impeachment inquiry into President Joe Biden as a pair of high stakes interviews with the president’s son, Hunter, and brother, James, over the next two weeks could determine the fate of their flailing investigation.

The closed-door interview with the president’s brother Wednesday comes as Republicans in recent weeks have hauled in a series of Biden family business associates who testified, based on first-hand experience, Joe Biden was not involved in his family’s foreign business dealings, undermining the allegation at the heart of their entire investigation. Hunter Biden is expected to show for his closed-door interview next week, after intense deliberations that almost collapsed.

It all amounts to a do-or-die moment for the Republicans leading the investigation, as they are up against serious doubts growing inside the GOP that they will be able to convince their razor-thin majority to back the politically perilous impeachment effort in an election-year. Top Republicans are expected to make an official decision on whether to pursue impeachment articles after the James and Hunter Biden interviews, sources told CNN. But the green light may need to ultimately come from rookie House Speaker Mike Johnson, who has struggled to make calls on key issues that are divisive to his conference.

James Biden was spotted on Capitol Hill entering his deposition shortly before 10:30 a.m. ET, and the interview ended a little over eight hours later.

He said in his opening statement that his brother “has never had any involvement or any direct or indirect financial interest” in his 50-year career in a variety of business ventures, according to a copy obtained by CNN.

“Because of my intimate knowledge of my brother’s personal integrity and character, as well as my own strong ethics, I have always kept my professional life separate from our close personal relationship,” James Biden said.

“I never asked my brother to take any official action on behalf of me, my business associates, or anyone else,” he added.

James Biden’s attorney, Paul Fishman, said in a statement that his client was “unequivocal” in his testimony that the president was not involved in his brother’s business ventures.

“Jim Biden was unequivocal that his brother played no role in, was not involved with, and received no benefits from any of Jim’s business ventures,” Fishman said. “The information that he provided confirms that this impeachment inquiry is a waste of time, resources, and taxpayer money.”

Since December, Republicans have interviewed eight people who worked closely with James and Hunter Biden, and none of the hundreds of pages of witness testimony provides evidence that the president was involved in or benefited from his family’s business ventures. Whether it was stopping by a business lunch, overseeing his bookkeeping, an exchange at a White House Fourth of July picnic or a phone call, business associates of the Biden family orbit said they never witnessed Joe Biden do anything wrong.

While Biden’s surface-level interactions that overlapped with his family’s business activities continue to provide fuel to his political opponents — particularly since the president remains adamant that he never interacted with any of them — the recent testimony has not uncovered evidence that meets the bar for high crimes and misdemeanors needed for impeachment, according to skeptical House Republicans.

And just last week, special counsel David Weiss charged a former FBI informant with lying about the president and his son Hunter Biden’s involvement in business dealings with Ukrainian energy company Burisma Holdings, undercutting a major aspect of Republicans’ impeachment inquiry. In another blow to Republicans’ impeachment effort, the ex-informant, Alexander Smirnov, told investigators after his arrest that Russian intelligence officials were involved in passing information to him about the younger Biden, prosecutors said Tuesday in a court filing, noting that the information was false.

After the latest bombshell, Republicans on Wednesday were asking the FBI why they ever relied on the informant in the first place, the latest example of how House Republicans are trying to downplay the informant they once championed.

“The DOJ and FBI have a lot of explaining to do about their reliance on the informant whose allegations were included in the FBI-generated FD-1023,” Oversight Committee Republicans wrote on X.

House Judiciary Chairman Jim Jordan refused to concede that the president was not involved in a bribery scheme when asked about the latest developments involving the informant.

Asked by CNN if he promoted false allegations, the Ohio Republican said, “not at all.”

Republicans hope James and Hunter Biden, who are the closest they have come to infiltrating the president’s inner circle, will provide new information about the elder Biden that will inject momentum into their inquiry. GOP investigators, in desperate search of a much-needed lifeline, are also looking to tie special counsel Robert Hur’s report on Biden’s handling of classified documents to their investigation. Democrats meanwhile see the interviews of the president’s son and brother as the lynchpin that could finally unravel the entire probe.

James Biden with his lawyer Paul Fishman on Wednesday.

Loan repayment checks from James Biden

In James Biden, Republicans have found their most direct piece of evidence that connects to the president in the form of two personal checks addressed to Joe Biden when he was not in office. But banking records reviewed by CNN provide substantial evidence that both were loan repayments and not the smoking gun Republicans had made them out to be.

The first check Republicans revealed went to Joe Biden in 2018 for $200,000 from James Biden and James’ wife Sara Biden. The check has the words “loan repayment” written on the front and was written to the president the same day that James Biden received $200,000 from a struggling health company he did business with.

The second check rolled out by Republicans, which also has the notation “loan repayment,” was from the president’s brother and wife to Joe Biden in September 2017 for $40,000.

House Oversight Chairman James Comer has repeatedly said he does not “believe” that Joe Biden had actually made a loan to his brother and claims the $40,000 check is “laundered China money.”

Democratic members of the committee and a lawyer for James Biden have said that Comer’s committee has documents that show there had indeed been a $200,000 loan from Joe Biden to James Biden. Banking records reviewed by CNN, which Comer’s committee possesses, provide substantial evidence in support of the Democrats’ assertions.

In his opening remarks Wednesday, James Biden addressed the two personal loan repayment checks. “The complete explanation is that Joe lent me money, and I repaid him as soon as I had the funds to do so,” he said, according to the copy of his remarks obtained by CNN.

He explained that “there have been a number of occasions when my personal financial obligations have exceeded our available funds.” He described the loans from Joe Biden as “short-term” that he received when his brother was a private citizen and repaid “within weeks.”

“He had no information at all about the source of the funds I used to repay him,” James Biden added.

The evidence CNN has reviewed is almost certainly only a fraction of the evidence Comer’s Republican-controlled committee has obtained, given that the committee subpoenaed years of financial records; the fraction CNN has seen does not prove with absolute certainty that there was a loan. But even this small batch of evidence clearly shows that the Democrats have documents at least partially substantiating their assertions about the check – and that Comer has not yet released some documents that undercut his efforts to raise public suspicions about the Bidens.

Beyond that, James Biden has touted his connection with his politically powerful brother, former business associates say, echoing claims that the president’s family sold the idea of the Biden brand in leveraging business dealings around the world. But that perception does not support claims made by Republicans including Comer, a Kentucky Republican who has painted Joe Biden as “A President Compromised” and framed the Bidens as a crime family.

To infiltrate James Biden’s orbit, Republicans interviewed Carol Fox, the bankruptcy trustee who oversaw the bankruptcy of Americore, the health care company James Biden worked with that paid him the same day he paid Joe Biden $200,000.

Fox alleged in a 2022 lawsuit that James Biden used “representations that his last name, ‘Biden,’ could ‘open doors’ and that he could obtain a large investment from the Middle East based on his political connections.”

While Fox had questions about James Biden’s role at Americore during her closed-door interview, she said she was not aware of any evidence that Joe Biden was involved in his brother’s business ventures.

In his opening statement, James Biden said, “My brother played no role, was not involved with, and received no benefits from my work with Americore.”

He said he did not think the $600,000 Americore paid him was a loan, but after court mediation, he repaid $350,000 in four increments.

“I continue to believe that I fully and fairly earned the $600,000 for services rendered,” he said.

Republicans have also interviewed Joseph Langston, who has known the president and his brother since the 1990s. Langston, who was convicted for trying to bribe a judge, has loaned James Biden money over the years and became involved in various business ventures with him.

Langston said he has not talked to Joe Biden in more than 15 years and said “absolutely not” when asked if Joe Biden received any money from business ventures he was involved in.

“Jimmy Biden has never once, in my experience, offered his brother’s participation, help, influence, in any business matter,” Langston said according to a transcript of his closed-door testimony.

James Biden, the brother of President Joe Biden, arrives with attorney Paul Fishman for a closed-door deposition with the House Oversight Committee at the Thomas P. O'Neill Jr. Federal Building on February 21 in Washington, DC.

What other Biden family business associates have said

Beyond Fox and Langston, Republicans have recently interviewed a number of key Biden family business associates.

Republicans called in Rob Walker, who worked with the Biden family on business pursuits in foreign countries including China and Romania and made wire transfers to companies associated with Hunter and James Biden. Walker also attended a 2017 business meeting with Hunter Biden and Chinese business associates, where Joe Biden made an appearance. Republicans have raised questions about the meeting because, shortly after, Walker received $3 million from the Chinese officials, a third of which was later sent to Hunter Biden and other Biden family members.

In his interview, Walker testified “to be clear, President Biden — while in office or as a private citizen — was never involved in any of the business activities we pursued. Any statement to the contrary is simply false.”

Walker said of the 2017 business meeting at the Four Seasons hotel in Washington, DC, that Joe Biden, who was then a private citizen, was there “maybe 10 minutes.”

“He spoke nice, you know, normal pleasantries,” Walker said of Biden. “I don’t believe, even really knew why they were there. He specifically said, ‘Good luck in whatever you guys are doing.’”

Asked why Joe Biden showed up in the first place, Walker said, “I don’t know, but I think that from time to time he liked to lay eyes on his son, who was in and out of sobriety.”

Walker said he has “no knowledge” that Joe Biden was aware of the payments he and his son received from the Chinese officials.

Another longtime Biden family business associate, Eric Schwerin, performed administrative and bookkeeping tasks for then-Vice President Joe Biden from 2009 to 2017.

“In the course of performing these duties, I had the ability to view transactions both into and out of Vice President Biden’s bank accounts while he was Vice President. Based on that insight, I am not aware of any financial transactions or compensation that Vice President Biden received related to business conducted by any of his family members or their associates, nor any involvement by him in their businesses – none,” Schwerin testified.

Mervyn Yan, a Chinese-American businessman who worked with Hunter and James Biden on a joint venture involving a Chinese-backed energy company that dissolved in 2018, testified he had “no contact” with Joe Biden.

Hunter Biden’s lawyer, Kevin Morris, said neither the president nor his administration had any role in deciding to loan Hunter Biden over $6.5 million.

Even the critical but unproven allegations against Joe Biden, brought by Tony Bobulinski, remain uncorroborated and have been undercut by other witnesses the committees have interviewed.

And while Hunter Biden’s art dealer, Georges Bergès, raised questions on the timeline of when the White House said ethical safeguards around Biden’s art were put in place and when the White House got involved, Bergès said he has “never” spoken to the president about the pricing of his son’s artwork.

Bergès, who told committee investigators he met the president when Hunter Biden’s daughter got married at the White House in 2022, recounted the one time the president called him.

“My daughter finished camp and he called to, you know, wish her, congratulate her for finishing camp, and I answered the phone,” Bergès said.

This story and headline have been updated with additional developments.

CNN’s Paula Reid, Manu Raju and Morgan Rimmer contributed to this report.