WASHINGTON — A special House committee looking into the deadly Benghazi, Libya, attacks in 2012 will interview a host of current and former high-ranking Obama administration officials as it speeds the pace of the investigation.

The panel’s chairman, Rep. Trey Gowdy, R-S.C., said Friday he intends to interview 20 high-ranking officials, including former Defense Secretary Leon Panetta and former CIA Director David Petraeus, as well as White House Chief of Staff Denis McDonough and National Security Adviser Susan Rice.

The list also includes former White House press secretary Jay Carney; Army Gen. Martin Dempsey, chairman of the Joint Chiefs of Staff; and former National Security Adviser Thomas Donilon.

Gowdy has previously said he will ask former Secretary of State Hillary Rodham Clinton to testify at a public hearing before the 12-member committee. He said Friday that appearance should occur “as soon as possible.” Clinton is widely expected to run for president in 2016.

Gowdy also said he wants to interview Cheryl Mills, a longtime Clinton aide who was her chief of staff when the attacks occurred at the U.S. diplomatic outpost.

Gowdy said last week he was frustrated at the slow pace of the investigation and was going to “ratchet it up.”

He said Friday that the interviews with the high-ranking officials will begin as soon as April, after the panel interviews 22 potential witnesses who work for the State Department or have knowledge of the attacks.

Gowdy called the timeline for new interviews “ambitious” but said he intends to “stay with this schedule and will issue subpoenas if necessary.”

The State Department agreed to interviews for the 22 witnesses last week but said that since many of the potential witnesses work overseas, the department “will need flexibility” about when the witnesses will appear.

Gowdy also plans to interview former UN Ambassador Thomas Pickering and Adm. Mike Mullen, who chaired an independent panel that reviewed the September 2012 attacks, which killed U.S. Ambassador Chris Stevens and three other Americans.

Pickering was President George H.W. Bush’s U.N. envoy, and Mullen was the top U.S. general under Presidents George W. Bush and Obama.

Their report harshly criticized the State Department for its security posture in the months before militants stormed the Benghazi facility. But House Republicans said their review was incomplete and lacked independence.