The chairman of the Senate Homeland Security Committee provided an update Wednesday on his panel’s investigation into potential corruption involving Ukrainian energy company Burisma Holdings and then-Vice President Joe Biden, who pressured the Ukrainian government to fire a prosecutor that was pushing to investigate the company, which was then employing Biden’s son.

An interim report on the investigation, said Senate Homeland Security Committee Chair Ron Johnson, will be released within the next two months, and it will likely include a document the panel believes may be key to determining if wrongdoing took place. The document involves a Washington-based firm representing Burisma, a Ukrainian energy company that was paying Biden’s son tens of thousands a month at the time to serve on its board despite his lack of expertise in the industry or region.

“These are questions that Joe Biden has not adequately answered,” Johnson told reporters Wednesday, as reported by Politico. “And if I were a Democrat primary voter, I’d want these questions satisfactorily answered before I cast my final vote.”

“My investigations are not focused on the Bidens. They’re just not,” Johnson said. “But I can’t ignore them because they’re part of the story. They made themselves part of the story. If there’s wrongdoing, the American people need to know it. If there is no wrongdoing or nothing significant, the American people need to understand that as well.”

The panel is likely to release its interim report within one to two months, Johnson announced.

In an interview with Fox News’ Martha MacCallum on Wednesday, Johnson said his committee is working to verify a document that describes an apology for the “misinformation campaign” against former Ukrainian Prosecutor General Viktor Shokin, who was working to investigate Burisma at the time Biden pressured Ukraine to remove him.

“I know it was a big explanation that everybody wanted him fired, but there is a document, we have to verify it, but there is a document supposedly contemporaneous that said that the contact by Blue Star to the prosecutor general’s office was all about apologizing for the misinformation campaign conducted against Shokin,” said Sen. Johnson, as reported by the Washington Examiner. “Kind of raises some eyebrows, some questions that need to be answered.”

Johnson highlighted the document in a recent memo to the committee saying that it might be necessary to subpoena employees of Blue Star Strategies, which, as the Examiner notes, “mentioned Hunter Biden in communications with the State Department in an apparent effort to improve its image in Washington, according to a Wall Street Journal report.”

Biden’s campaign responded to Johnson’s statement about the Democratic frontrunner on Wednesday, telling Politico that the committee chair just did them “an enormous favor.”

“Senator Johnson just accidentally did us an enormous favor by explicitly admitting that he is abusing congressional authority in a manner that would make the founding fathers spin in their graves,” said campaign spokesman Andrew Bates.

But Trump sees things differently. In an appearance on Fox News Wednesday night, the president called Burisma “a major issue” for Biden’s campaign and promised to “bring that up all the time because I don’t see any way out” for Biden.

As Biden has openly touted, when he was heading up U.S.-Ukraine relations, he threatened to withhold a billion dollars of aid to Ukraine if Shokin was not removed. The gambit worked and Shokin was ousted in March 2016. Shokin claims he was removed specifically because he was working to investigate Hunter Biden’s lucrative Burisma deal, which started in 2014 and lasted over four years. The issue was at the heart of the Democrats’ impeachment of Trump, as the president asked Ukrainian President Volodymyr Zelensky in the famous July 25 call to “look into” the question of potential corruption involving Burisma and the Bidens.