WASHINGTON » Attorney General Eric Holder told Congress today that a serious national security leak required the secret gathering of telephone records at The Associated Press as he stood by an investigation in which he insisted he had no involvement.

Pestered by Republicans and some Democrats, Holder testified that he has faith in the individuals conducting the broad investigation, driven in large part by GOP outrage last year over the possibility that administration officials leaked information to enhance President Barack Obama’s national security reputation in an election year.

Holder said he had recused himself from the case because "I am a possessor of information eventually leaked." He said he was unable to answer questions on the subpoenas and why the Justice Department failed to negotiate with the AP prior to the subpoenas, a standard practice.

That elicited frustration from some committee members with the Obama administration and the attorney general.

"There doesn’t appear to be any acceptance of responsibility for things that have gone wrong," Rep. James Sensenbrenner, R-Wis., told Holder. He suggested that administration officials travel to the Harry S. Truman Presidential Library and take a phone of the famous sign, "the buck stops here."

It was the Justice Department’s No. 2 official, Deputy Attorney General James Cole, who made the decision to seek news media phone records, Holder said.

Last year, Holder appointed two U.S. attorneys to lead a Justice inquiry into who leaked information about U.S. involvement in cyber-attacks on Iran and an al-Qaida plot to place an explosive device aboard a U.S.-bound flight. Holder had resisted calls for a special counsel, telling lawmakers that the two attorneys, Ron Machen and Rod Rosenstein, are experienced, independent and thorough.

Holder was grilled on several scandals rocking the administration, including the targeting of conservative groups by the Internal Revenue Service and any missteps in sharing intelligence information prior to the bombings in Boston.

Responding to news of the gathering of AP records, Sen. Chuck Schumer, D-N.Y., planned to revive a 2009 media shield bill that protects journalists and their employers from having to reveal information, including the identity of sources who had been promised confidentiality.

The law does contain some exceptions in instances of national security.

"This kind of law would balance national security needs against the public’s right to the free flow of information," Schumer said in a statement. "At minimum, our bill would have ensured a fairer, more deliberate process in this case."

The White House threw its support behind the legislation, said a White House official, who was not authorized to speak on the record about the topic and demanded anonymity. Ed Pagano, President Barack Obama’s liaison to the Senate, placed a call this morning to Schumer’s office to ask him to revive the bill, a move the senator had planned to make.

Obama’s support for the bill signaled an effort by the White House to show action in the face of heated criticism from lawmakers from both parties and news organizations about his commitment to protecting civil liberties and freedom of the press.

White House officials have said they are unable to comment publicly on the incident at the heart of the controversy because the Justice Department’s leak probe essentially amounts to a criminal investigation of administration officials.

Holder on Tuesday defended the move to collect AP phone records in an effort to hunt down the sources of information for a May 7, 2012, AP story that disclosed details of a CIA operation in Yemen to stop an airliner bombing plot around the anniversary of the killing of terrorist leader Osama bin Laden. The attorney general called the story the result of "a very serious leak, a very grave leak."

Sen. Dianne Feinstein, D-Calif., chairwoman of the Senate Intelligence committee, said today that the leak was "within the most serious leaks because it definitely endangered some lives."

Feinstein said it was her understanding that the information gathering did not focus on the "content of phone calls," but rather "to see who reporters have spoken to, that somebody did provide this information with respect to this bomb."

At a news conference Tuesday, Holder defended the subpoenas to the AP and disclosed that the department was investigating the IRS for giving tea party groups extra scrutiny when they applied for tax exempt status.

Documents obtained by the AP suggest the targeting of conservative groups could be more widespread than the IRS has acknowledged. The agency has said it was limited to low-level workers in a Cincinnati office.

At Tuesday’s news conference, Holder said the U.S. has gotten good cooperation from the Russians on the Boston bombings investigation. U.S. law enforcement officials are trying to determine whether Tamerlan Tsarnaev was indoctrinated or trained by militants during his visit to Dagestan, a Caspian Sea province of Russia that has become the center of a simmering Islamic insurgency.

Associated Press writers Josh Lederman, Erica Werner and Donna Cassata contributed to this report.