IRS officials are so aggressively stonewalling a congressional investigation of illegal political targeting by the tax agency that the House Oversight Committee may have to start issuing subpoenas, according to the panel's chairman.

"Despite your promise to cooperate fully with congressional investigations, the actions of the IRS under your leadership have made clear to the committee that the agency has no intention of complying completely or promptly with the committee's oversight efforts," Rep. Darrell Issa, R-Calif., told acting IRS Commissioner Danny Werfel in a blistering letter made public Tuesday.

The IRS has released approximately 13,000 pages of documents sought by the oversight committee in its probe of illegal harassment of Tea Party, conservative and evangelical groups seeking tax exemption during the 2010 and 2012 election campaigns.

But the 13,000 figure is a minute portion of the 64 million documents in its files that the IRS told the committee months ago could be relevant to its investigation.

If subpoenas are issued to the IRS, it won't be the first time in recent years when a House committee reached for one of its ultimate weapons after being denied access to important documents by executive branch officials.

A Washington Examiner survey of oversight efforts by eight House committees found multiple instances of document requests getting the cold shoulder from the Obama administration.

The Examiner interviewed multiple majority staff aides -- all of whom spoke only on condition of anonymity -- and looked at more than 100 major document requests to the White House and executive branch departments and agencies since the start of the 112th Congress after House Republicans regained a majority in the 2010 election.

Nearly half of the requests were denied outright, answered with irrelevant or inadequate materials, or seriously delayed. As might be expected, the White House, including the Office of Management and Budget, is the most difficult to deal with, according to committee aides.

The Energy and Commerce Committee, for example was forced to issue subpoenas when White House officials refused to answer eight of the panel's 11 requests, beginning in 2011.

"The White House was an epic battle," said an aide.

Things were even tougher during the 2012 campaign. A veteran energy and commerce committee aide departments and agencies could be slow to respond under President George W. Bush, but the Obama administration has taken the "tug of war" for information to a whole new level.

"This is different in caliber," the aide said.

Inadequate responses were received on eight of 17 major document requests sent by the Committee on Education and the Workforce to the National Labor Relations Board, Department of Labor, Health and Human Services and OMB since October 2011. All but two of those responses were late in being delivered.

Sometimes committee requests are simply ignored by Obama officials in the executive branch. Letters to the Editor from the Committee on Homeland Security, for example, to the Department of Homeland Security, FBI and the Office of National Intelligence in April following the Boston Marathon bombings were ignored.

So were letters to DHS about the Texas fertilizer plant explosion, and letters to DHS and Immigrations and Customs Enforcement about border security, according to committee aides.

Ninety percent of the requests from the House Natural Resources Committee to the Department of Interior in 2012 and 2013 either received late responses or were denied outright.

Committee Chairman Doc Hastings, R-Wash., told Secretary of the Interior Sally Jewell during a July 17 hearing that her department has refused to comply with 10 of the panel's requests.

"I know our teams have met multiple times and I will renew my offer to you which is before you feel a need to submit a document request, I'm very happy to have a one-on-one conversation with you to understand -- I appreciate the role of oversight of this committee and I'm committed to upholding that," Jewell responded.

"And if there is a way we can do it without having people go through laborious document requests and then you're having to review those document requests, that would be great because I think we share a commitment to a transparent relationship," she said.

Even when agencies do respond, it's often long after the customary two-week deadline used by the committees, sometimes as much as a year late and often only after repeated follow-up letters, telephone calls and emails.

Late responses were received for 13 of the 15 Committee on Education and the Workforce requests. The House Science, Space and Technology committee also said responses to document requests in its investigations are often late.

"The administration has been consistently late on the deadlines we give them -- probably an average of two months behind schedule," an aide said.

White House and executive branch spokesmen did not respond to multiple requests for comment.