The GOP-led House panel probing the 2012 Benghazi attack has put off plans for a hearing with Hillary Clinton, telling Secretary of State John Kerry in a letter that State's failure to release documents is standing in the way.

"The only thing standing between the Committee and the former Secretary being able to discuss her tenure as Secretary of State as it relates to Libya and Benghazi is the Department of State's failure, in more than half a year, to produce a single, solitary email responsive to our request and subpoena," wrote Rep. Trey Gowdy, chairman of the Select Committee on Benghazi.

Gowdy last month had floated the idea of a hearing to take place as soon as May 18, but now says that lawmakers need more information to inform their questions to Clinton about the fatal attacks and her use of a private email server for State Department business.

"There is still the possibility of scheduling the former Secretary's appearance soon, but that is contingent upon Department of State compliance," Gowdy wrote.

Democrats on the panel allege that Gowdy is delaying the hearing and slow-walking the probe for political reasons.

The panel's Republicans have put the ball in Kerry's court and still haven't picked a firm date, but in the meantime, they're preparing for the high-stakes phase of the probe.

Since House Republicans created it a year ago, the Select Committee has kept a low-profile by design, doing most of its probe of the fatal 2012 events outside of public view. But the political glare will soon get much brighter.

A hearing with Clinton will draw massive press scrutiny of not only the Democratic frontrunner, but also her GOP inquisitors, whom Democratic lawmakers and Clinton's political allies accuse of using the process to wound Clinton in the presidential race.

Republicans on the panel have tried to avoid giving off any whiff of politics, even as the Republican National Committee has sought to batter Clinton's electoral prospects with attacks on her email practices.

Ask the House Benghazi committee's Republican members about their plans and you'll get a just-the-facts-ma'am take on the panel's role probing the fatal Benghazi attack, as well as Clinton's use of a private email system for State Department business.

"We would be making the same type of inquiry and conducting ourselves in the same way if it was Secretary Rice or Secretary Powell," said Rep. Susan Brooks, referring to George W. Bush's secretaries of State.

Gowdy was dismissive when asked about the spotlight on Clinton's appearance before the panel. "I don't have any control over scrutiny. You guys decide what's scrutinized and what is not. We have had three public hearings and I have not mentioned her name," Gowdy said.

Both lawmakers spoke to National Journal ahead of Thursday's announcement.

Clinton's appearance will be a high-stakes political affair regardless of what Republicans say about their goals. The pro-Clinton group Correct the Record, which has pushed back against the Benghazi probe, is preparing for rapid-response as Republicans question Clinton.

Adrienne Watson, a spokeswoman for the group, says they will be "ready and nimble" with its press work "as required by the antics of Gowdy's political circus."

The latest flare-up came last week. A committee report on its activities to date said the panel would call Clinton to testify "once it is satisfied that all the relevant information has been provided by both the State Department and her."

Democrats quickly accused Republicans of delaying the Clinton appearance, noting the report signals that Republicans are backing off their plan to have Clinton—who has said through her lawyer that she's ready and willing to testify—appear the week of May 18.

"At every turn, the Select Committee comes up with a new excuse to further delay its work and then blames its glacial pace on someone else," said Rep. Elijah Cummings, the top Democrat on the panel, said last week.

"Republicans are desperately trying to validate the $3 million in taxpayer funds they have spent over the past year, but they have nothing to show for it other than a partisan attack against Secretary Clinton and her campaign for president," he said.

A mid-April letter from Gowdy to Clinton's lawyer said he wanted to hold a hearing that week on her emails and a second one later about the Benghazi attacks. Clinton's lawyer this month rejected the idea of two hearings.

But Republicans insist that they're still awaiting important documents and that the Obama administration's lack of responsiveness has hobbled the investigation.

And Gowdy said that if they're only going to get one chance to question Clinton, they need to come armed with as much information as possible.

"I am not going to ask my members, if they are going to have one opportunity to have a constructive conversation with Secretary Clinton, I am certainly not going to ask my members to have that conversation without the documents they need," he said.

"I try very hard not to tell people in your line of work how to do their job and you all have been really good about not telling me how to do mine, but at some point somebody does need to ask the State Department [why] six months is not long enough to produce emails," Gowdy added.

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