(CNN) Two Republican Senate committee chairmen requested Hunter Biden's travel information from when his father, Joe Biden, was vice president from the Secret Service director on Wednesday following the Senate's vote to acquit in the impeachment trial of President Donald Trump.

Finance Chairman Chuck Grassley, of Iowa, and Homeland Security and Governmental Affairs Chairman Ron Johnson, of Wisconsin, announced in a letter to Secret Service Director James Murray that their panels "are reviewing potential conflicts of interest posed by the business activities of Hunter Biden and his associates during the Obama administration."

The chairmen's timing is notable, as the impeachment trial centered largely on Trump's attempts to pressure Ukraine to investigate Hunter Biden and Joe Biden, his potential political rival. Trump has repeatedly made unfounded and false claims to allege that the Bidens acted improperly in Ukraine.

"We write to request information about whether Hunter Biden used government-sponsored travel to help conduct private business, to include his work for Rosemont Seneca and related entities in China and Ukraine," the chairmen wrote, referencing a firm co-founded by Hunter Biden.

CNN has reached out to the Secret Service for comment. A spokesperson for Joe Biden's presidential campaign declined to comment.