Two GOP Senate chairmen said on Thursday that their staffs will interview a former business associate of Hunter Biden's, and that they are requesting documents from former Vice President Joe Biden's son, as they revive their investigation just weeks before the election. 

Sens. Ron Johnson (R-Wis.) and Chuck Grassley (R-Iowa) said they had sent letters to five individuals, including attorneys for Hunter Biden, requesting documents, and will interview Tony Bobulinski, a former Army intelligence officer who claims to have managed the Bidens' foreign business portfolio at one time, on Friday.

The requests for documents comes as President Trump, who is trailing in the polls, and his allies are seizing on a New York Post story that alleges that Hunter Biden used his influence to connect a businessman and fellow board member at Ukraine gas company Burisma with his father when he was vice president.

“As part of the committees’ efforts to validate the authenticity of recently publicly released emails involving the Biden family’s international financial entanglements, we sent letters to five individuals identified in the emails. Those letters were sent yesterday, and the deadline is October 23, 2020," Johnson and Grassley said in a joint statement.  

"So far, the committees have received a response only from Mr. Tony Bobulinski, who appears to be willing to fully cooperate with our investigation. In fact, Mr. Bobulinski has already agreed to appear for an informal interview by the committees tomorrow, Friday, October 23, 2020," they added. 

Emails from Bobulinski — who Trump is expected to bring to a debate on Thursday night against Joe Biden, the Democratic presidential nominee — were a key part of the Post's story. The Post says that it got a copy of the hard drive from Trump's attorney Rudy Giuliani. 

National security experts and Democrats have said the way that the emails were discovered — through a laptop that Hunter Biden allegedly dropped off at a repair shop and never picked up — raise concerns that it could be part of a Russian disinformation campaign.

The Washington Post, citing four former intelligence officials, reported last week that the White House was warned last year that Giuliani was the target of an influence operation by Russia with concerns that Giuliani could be feeding Russian disinformation to Trump. 

Director of National Intelligence John Ratcliffe, who Trump appointed, has said publicly there is no evidence of a foreign disinformation campaign, despite the statements from intelligence officials and experts, some of whom have also spoken to The Hill.

Johnson and Grassley, as part of their email to Hunter Biden's attorneys, are requesting records related to business dealings — including business transactions and travel and bank records — with several individuals including Joe Biden and his brother James Biden, as well as copies of any communications related to the business dealings. 

The requests for documents, and decision to interview Bobulinski, comes after Johnson and Grassley ran a months-long investigation into Hunter and Joe Biden. 

Though their report released last month accused Hunter Biden's work for Ukraine gas company Burisma Holdings of casting a "shadow" over Obama-era foreign policy, they didn't list a specific example of an instance where U.S. foreign policy was changed because of Hunter Biden. 

Johnson defended the investigation, arguing that it wasn't being driven by Joe Biden's campaign. But he also argued that his findings would raise questions about the former vice president's "fitness for office." 

Johnson appeared to have turned his focus toward the FBI and the Russia probe in recent weeks, as part of a separate investigation he's running, but his committee said following the Post story's publication that it would attempt to "validate the information." 

In addition to the letters released on Thursday, Johnson sent a letter to FBI Director Christopher Wray last week about the laptop and is requesting that FBI Inspector General Michael Horowitz investigate the bureau's handling of the laptop that allegedly belongs to Hunter Biden. Johnson and Grassley have also requested additional details about Hunter Biden's travel from the Secret Service. 

A spokesman for Joe Biden's campaign didn't immediately respond to a request for comment on the request from Johnson and Grassley. But the Biden campaign has disputed the Post story, which has not been verified by other major outlets, noting that his official schedule at the time did not list any such meeting.

And Biden, in a recent TV interview, said Johnson should be "ashamed" of his claim that Hunter Biden profited off of his last name. 

“It's the last-ditch effort in this desperate campaign to smear me and my family," Biden told WISN 12 News.