After nearly a year and a half, House Republicans on Thursday will get their chance to question Interior Department officials over the editing of an agency report that mistakenly suggested an independent group of experts had endorsed a halt on deepwater drilling following the BP PLC spill in the Gulf of Mexico.

Neal Kemkar, special assistant to the counselor to Interior Secretary Ken Salazar, and Mary Katherine Ishee, deputy chief of staff to the assistant secretary for land and minerals management, have agreed to testify before the House Natural Resources Committee as part of its ongoing investigation into who may be responsible for the report's error and whether it was added intentionally to provide political cover for the Gulf moratorium.

Committee Chairman Doc Hastings (R-Wash.) last month invited the two to testify, saying they had direct knowledge of or involvement in the drafting, editing or reviewing of the agency's May 2010 drilling safety report.

Kemkar personally assisted in the development of the report, communicated with the peer reviewers and exchanged edits with White House staff. But investigators in the Office of Inspector General did not seek documents from him, committee Republicans said. In addition, the OIG never interviewed Ishee or sought documents from her.

Hastings last month said the hearing comes after much frustration over Interior's cooperation with the committee's investigation.

"The department has ignored a subpoena for documents, refused requests for transcribed interviews with five department officials, refused to confirm the attendance of the five officials at a July committee hearing, and forced the committee to vote to authorize the issuance of subpoenas to compel these and potentially other individuals to testify," he said. "It took subpoenas becoming a reality for the department to agree to have these individuals appear voluntarily."

Hastings said he hopes to better understand the administration's rationale for imposing the moratorium, which many blame for thousands of lost jobs, economic hardship and rigs leaving the Gulf of Mexico.

An Interior spokesman last week declined to comment on the upcoming hearing. But the agency has long argued it has provided nearly 2,000 pages of documents and remains willing to cooperate with the committee's "legitimate oversight interests."

Former press secretary Adam Fetcher earlier this summer called the committee's continued probe a waste of taxpayer money, arguing Republicans continue to litigate an issue that was solved years ago.

Democrats on the committee have also panned the investigation as a political smear tactic in the heat of election season, criticizing Republicans for failing to strengthen offshore drilling safety or ask the chief executives of the companies responsible for the spill to testify.

On Friday, an industry consultant who was hired to assist in Interior's report said Salazar had done all he could to apologize both publicly and privately to the peer reviewers and others involved in the report.

"I feel that's an appropriate response for the secretary to make," said Ken Arnold of K Arnold Consulting Inc. in Houston. "Whether it was an accident or someone did this on purpose, I don't think anybody will ever know. You could make the case either way, but it doesn't matter. He apologized. He apologized publicly, he apologized privately."

Arnold said drilling experts in subsequent discussions told Interior they understood the agency's rationale for a moratorium but suggested it be modified to allow some drilling to continue.

He was critical of the committee's ongoing probe.

"The rest of this is just a witch hunt, it's a political witch hunt to make the Obama administration look bad," Arnold said. "It has nothing to do with anything that will change the way in which we drill or the way in which we protect the environment. It is a waste of Congress' time."

Robert Bea, a professor emeritus at the University of California, Berkeley, who was among seven peer reviewers cited in the report, said the current investigation fails to address key safety issues facing the offshore industry.

"I think the current investigation is not addressing the critical issues that confront the federal and state governments, the oil and gas industry, and the public concerning the 'very high risk projects' we are currently undertaking and propose to undertake in development of offshore oil and gas resources," he said in an email.

Hastings last month also issued subpoenas for Kemkar and Ishee to provide copies of "all documents that were created, sent or received by them between April 26, 2010, and June 30, 2010, related to the development, editing, review, issuance, response, or reaction to the Drilling Moratorium Report."

Schedule: The hearing is Thursday, Sept. 13, at 10 a.m. in Longworth 1324.

Witnesses: Neal Kemkar, special assistant to the counselor to the Interior secretary; Mary Katherine Ishee, senior advisory and deputy chief of staff to the assistant secretary for land and minerals management.