WASHINGTON — House Republicans said Friday they’ll seek to form a select committee to investigate the 2012 terrorist attacks on the U.S. mission and CIA annex in Benghazi, Libya.

House Speaker John Boehner’s call for a special panel coupled with House Oversight and Government Reform Committee Chairman Darrell Issa’s subpoena compelling Secretary of State John Kerry to testify about the attacks signals a new and more aggressive phase of Republican attempts to blame the Obama administration for the deaths of U.S. Ambassador J. Christopher Stevens and three other Americans.

The moves will keep a spotlight on Benghazi — an issue that revs up the Republican and conservative base — in a congressional election year and ahead of the 2016 presidential contest in which former Secretary of State Hillary Rodham Clinton is a potential Democratic candidate. She oversaw the State Department when the assaults occurred on Sept. 11, 2012.

“You create a special committee if you want a bigger spotlight on a subject, which is more 2014-, 2016-related,” said Norman Ornstein, a resident political scholar at the center-right American Enterprise Institute. “With Benghazi, while it’s true he (Issa) is bringing in Kerry, most of the focus is on Clinton.”

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Many of the original charges that blamed the Obama administration for the deaths have never held up. But Republicans ramped up their efforts again this week with the emergence of new emails that they have labeled a “smoking gun.”

Boehner, R-Ohio, said the emails showed the White House has withheld documents from congressional investigators and asked: “What else about Benghazi is the Obama administration still hiding from the American people?”

No lawmakers were named to the select committee Friday, but Rep. Trey Gowdy, R-S.C., a former federal prosecutor, is reportedly being considered to chair the panel.

At the State Department, officials expressed surprise and dismay about Issa’s subpoena.

Issa, R-Calif., wants Kerry to testify May 21, a date the secretary is scheduled to be in Mexico.

Issa’s subpoena came a day after retired Air Force Brig. Gen. Robert Lovell, who was on duty in Germany during the Benghazi attack, told Issa’s committee that U.S. military personnel knew the assault on the U.S. facilities was a “hostile action” and not a protest gone wrong, as the White House initially said.

Lovell said that as the attack raged, military command held discussions “that churned on about what we should do.” He testified that the command was “waiting for a request for assistance from the State Department.”

But a leading Republican voice on military issues, House Armed Services Committee Chairman Howard “Buck” McKeon of California, undercut Lovell’s claims by issuing a statement calling Lovell an unreliable witness.

“BG Lovell did not serve in a capacity that gave him reliable insight into operational options available to commanders during the attack, nor did he offer specific courses of action not taken,” McKeon said in a statement. “The Armed Services Committee has interviewed more than a dozen witnesses in the operational chain of command that night, yielding thousands of pages of transcripts, emails and other documents. We have no evidence that Department of State officials delayed the decision to deploy what few resources (Department of Defense) had available to respond.”

Since opening its investigation in October 2012, Issa’s committee has produced no proof of the key Republican charges that the Obama administration failed to adequately respond to the attacks and purposely misled the nation about what happened to safeguard Obama’s campaign for a second term, which he in part based on his record fighting terrorism.

The email that Republicans seized on this week showed a White House official urging Susan Rice, who was then the ambassador to the United Nations, to defend the president’s policy in the region in television appearances three days after the attack and to emphasize that the riots occurring throughout the Middle East at the time were prompted by an anti-Muslim Internet video.

The email was released as part of a lawsuit by a conservative group, Judicial Watch.

Material from The New York Times is included in this report.