Darrell Issa’s bluff on the IRS investigation is being called in a big way by top Democrats on Issa’s House Oversight Committee. In a letter sent today to Issa, they are demanding he explain in more detail why he continues to refuse to release full transcripts of witness testimony on the IRS scandal — and they are giving him until Monday to do so.

As you know, Democrats have been pressing Issa — the House GOP’s leading investigations ringleader — to release full transcripts of testimony given to the Committee, which Issa chairs, in the course of its investigation into the IRS scandal. Issa has released selected snippets of that testimony, and has suggested — without substantiation — that the White House directed the IRS targeting of conservative groups.

Rep. Elijah Cummings, the ranking Oversight Committee Dem, says the full transcript of testimony will show the charges to be false, and will reveal Issa’s selective leaking for what it is. In particular, Cummings wants the full transcript released of testimony by the IRS Screening Group Manager in Cincinnati, a conservative Republican. Cummings says his testimony will show that there is no evidence of White House involvement in the development of the screening of Tea Party cases — and that the process by which these cases got referred to Washington officials falls far short of the conspiracy alleged by conservatives.

Issa has since replied that releasing the full transcripts — as opposed to selected snippets of it — would be “reckless” and “irresponsible,” because it would “serve as a roadmap of the Committee’s investigation” in a way that could discourage future witnesses.

Now Dems on the Oversight Committee are calling Issa’s bluff. In a letter that was sent to Issa today, Cummings asks Issa to specify precisely how releasing full transcripts would harm the investigation, and even agrees to conceal any parts of them that would, according to Issa, do that.

Cummings asks for a reply by Monday, which strongly suggests he will release the full transcripts himself if Issa doesn’t respond. From the letter:

In order to move forward in a responsible manner, I propose the following approach.  I am attaching for your review a copy of the transcript of the Committee’s interview of the IRS Screening Group Manager in Cincinnati.  In this copy, the names of individuals have been redacted to protect their privacy.  In order to provide the public with the most comprehensive information possible without jeopardizing the Committee’s investigation, I request that you review this version of the transcript and identify any specific text you believe should be withheld from the American people, as well as the specific reason you believe that text should continue to be concealed from public view.  I request that you provide any additional proposed redactions on Monday, June 17, 2013.
In addition, since you have not sought my input on a protocol for how to handle the release of interview transcripts, I propose that our staffs meet to discuss a bipartisan procedure to handle these types of issues in the future.  As I made clear on Sunday, although I fundamentally disagree with the unsubstantiated claims you have made about the IRS matter being driven by the White House to attack the President’s political enemies, you are the Chairman of this Committee, and I want to give you appropriate deference in conducting investigations.  I believe we should proceed in a responsible manner in order to uphold the integrity of the Committee, and I continue to hope that we can focus in a bipartisan manner on an approach that maximizes transparency and accuracy.

Issa has already been pilloried by news organizations for failing to substantiate his more lurid charges of White House involvement in the IRS targeting, and his answer to this challenge will likely be seen by news orgs as another test of his credibility. If Cummings is right, and the transcripts dramatically undercut Issa’s claims, it’s unclear what Issa’s endgame is here.