WASHINGTON - D. Kyle Sampson, the former chief of staff to Attorney General Alberto Gonzales who orchestrated the firing of eight U.S. attorneys, then resigned amid the political fallout, will testify voluntarily before the Senate Judiciary Committee on Thursday. "I welcome Mr. Sampson's decision to testify voluntarily, in public and under oath," committee Chairman Patrick Leahy, D-Vt., said in a statement. "Mr. Sampson is a key figure in this matter, having played an integral role in the planning and execution of the firings and replacements of these prosecutors, along with White House political advisers." Leahy had scheduled a hearing for next week, but Sampson's attorney and friend, Bradford Berenson, asked to have it postponed to give him more time to review documents and to take a planned family vacation to Utah. On Friday, Berenson agreed to go ahead with the hearing as scheduled. "His appearance is voluntary, and no subpoena will be necessary," Berenson said. "Mr. Sampson looks forward to answering the committee's questions." Sampson resigned his position earlier this month. Gonzales said he failed to fully inform the Justice Department officials testifying to Congress. But Berenson issued a statement on March 16 in which he said Sampson did not mislead anyone, but resigned because he felt he had failed to prepare an adequate response. The Senate committee had given Leahy authority to issue a subpoena for Sampson if he did not comply voluntarily. Leahy said he hopes others will be willing to appear on their own. - Robert Gehrke