"Based on recent protected disclosures to my office, the FBI has within its possession significant, impactful and voluminous evidence with respect to potential criminal conduct by Hunter Biden and James Biden," Sen. Chuck Grassley (R-Iowa) told FBI Director Christopher Wray and other officials in a letter dated Oct. 13.

James Biden is the president's brother.

Grassley, the top Republican on the Senate Judiciary Committee, has been approached by a number of whistleblowers in recent months about how the bureau has handled its investigation of Hunter Biden, who carried out business in China and other countries while his father was vice president.

The evidence of possible criminal activity includes a summary of an interview FBI agents had conducted with Tony Bobulinski, Hunter Biden's onetime business partner, shortly before the 2020 presidential election.

"In that interview, Mr. Bobulinski stated that the arrangement Hunter Biden and James Biden created with foreign nationals connected to the communist Chinese government included assisting them with potential business deals and investments while Joe Biden was Vice President; however, that work remained intentionally uncompensated while Joe Biden was Vice President. After Joe Biden left the Vice Presidency, the summary makes clear that Hunter Biden and James Biden worked with CEFC and affiliated individuals to compensate them for that past work and the benefits they procured for CEFC," Grassley wrote.

CEFC China Energy, now defunct, was a large energy firm in China.

According to the summary, Grassley said, Hunter Biden, James Biden, and their associates created a venture that would enable them to be compensated.