Republicans pushed embattled Attorney General Eric Holder on Tuesday to appoint a special prosecutor to investigate how highly classified information was leaked, apparently from inside the Obama administration.

Holder's decision to have the leaks investigated by two U.S. attorneys was dismissed as inadequate by the GOP. "The U.S. attorneys are under your personal supervision," said a letter signed by 31 GOP senators and circulated by Sen. Lindsey Graham of South Carolina. "An outside special counsel, with the appropriate independence and authority, would ensure that the investigation remains untainted by even the appearance of politics or undue influence."

The leaks that prompted the calls for an outside inquiry involved two New York Times reports one on a U.S. cyber-attack on the Iranian nuclear program and another on the White House's secret list of Muslim insurgents targeted for killing and

The leaks exposed tactics, technology, procedures, said Steven Bucci, a former Pentagon aide who is now a senior research fellow at the Heritage Foundation. "These leaks really are damaging, regardless of the reasons. People in authority need to be held accountable," he said.

The senators singled out national security adviser Thomas Donilon in their letter. When asked about Donilon at the new conference, Republican Sen. John McCain of Arizona said he wasn't ready to "indict" anyone without evidence. But McCain said the leaks appeared to be motivated by politics.

President Obama has publicly condemned the leaks and said anyone inside the administration proved to be involved in them would be punished.

The FBI is conducting a separate investigation into the leaks.

Holder has assigned the leak probe to District of Columbia's federal prosecutor, Ronald C. Machen Jr., and Rod J. Rosenstein, the U.S. attorney for Maryland. He promised to "follow the facts and the evidence in the pursuit of justice, wherever it leads."

Sara A. Carter is The Washington Examiner's national security correspondent. She can be reached at