A whistle-blower said the tax agency found a message from 2017 in which Hunter Biden pressured a Chinese business partner by saying he was with his father, who was then out of office.
The move by the G.O.P.-led House was the first in what could be a series of votes seeking to punish those whom Republicans have deemed enemies of the party.
The attorney general has confronted an unrelenting succession of politically sensitive investigations, underlining the intensely polarized environment he is operating in.
Under an agreement with the Justice Department, the president’s son agreed to probation for filing his taxes late, and he can avoid a charge that he lied about his drug use when he bought a gun.