A fierce debate today among House Oversight and Government Reform Chairman Darrell Issa (R-Calif.), ranking member Elijah Cummings (D-Md.) and the Justice Department was missing something crucial: the documents they were arguing about.

Issa fired the first shot in a letter to Attorney General Eric Holder claiming six wiretap applications that his committee obtained contain “shocking” revelations — that senior Justice officials were briefed, and approved, the tactics at the heart of the Fast and Furious scandal.

The wiretap applications, however, were not attached. They are under court seal, making it illegal to release them, or, for that matter, give them to Issa.

Democrats quickly pushed back, arguing the wiretaps were mostly reviewed by low-level line attorneys. But their full argument to that effect is, like the documents, unknown.

A June 5 response letter from Cummings said Issa “omits the critical fact that [redacted].” The entire first section of the letter’s body is likewise blacked out.

In Fast and Furious, agents for the Bureau of Alcohol, Tobacco, Firearms and Explosives allowed assault guns to “walk,” which meant ending surveillance on weapons suspected to be en route to Mexican drug cartels.

The tactic, which was intended to allow agents to track criminal networks by finding the guns at crime scenes, has been roundly condemned after two guns that were part of the operation were found at border agent Brian Terry’s murder scene.

After initially denying the tactic was ever used, the DOJ conceded it was but insisted that senior officials were not aware of its use.

Issa’s allegation gets to the heart of the debate.

Justice Department spokeswoman Tracy Schmaler said Issa’s allegations were false. But she couldn’t say what was in the wiretap applications either.

“The Department cannot comment on the contents of court-sealed applications — and it is very concerning that such documents relating to ongoing criminal cases have been leaked,” Schmaler said.

Lanny Breuer heads the Justice Department’s criminal division which approves the wiretap applications. Issa spokesman Frederick Hill said Deputy Assistant Attorney General Jason Weinstein, Deputy Assistant Attorney General Kenneth Blanco and a third official who has since died actually signed the applications.

According to Cummings, Weinstein flatly denied knowledge of the tactics in Fast and Furious until much later, when they were first reported in the media in January 2011, in an interview with committee investigators. Cummings argued that the applications were only reviewed narrowly, for whether enough evidence was present for probable cause, the legal criteria for obtaining a wiretap.

Issa’s office argued that the responsibility still lies with Breuer, even if he had deputies reviewing the wiretaps on his behalf.

“Breuer is charged, by statute, with responsibility for approving these wiretaps. The department specifically designated Breuer as the person responsible for the sign-off and his assistants signed under his name,” Hill said.

Amid the recriminations, Deputy Attorney General James Cole sent a letter to Speaker John Boehner (R-Ohio), Majority Leader Eric Cantor (R-Va.), Majority Whip Kevin McCarthy (R-Calif.) and Issa, saying the Justice Department and House officials have “had a number of constructive conversations with staff” since the House leaders wrote Holder on May 18.

“These conversations stand in contrast with the tone and content of the letter that Chairman Issa made public today,” Cole wrote.

Though Cole vigorously disputed Issa’s characterization of the contents of the wiretap applications, Cole wrote he is “legally prohibited from commenting on the content” of them.

Cantor said at a pen-and-pad meeting with reporters today that a hearing Thursday where Holder is testifying will be crucial to whether Republicans decide to hold Holder in contempt of Congress.

“Holder is coming before the Judiciary Committee this Thursday, and he’s going to have to answer to a lot of concerns that our members have and that I have and that I know the Speaker has,” Cantor said.

“We remain committed to moving on this contempt issue if the Justice Department and the administration and Holder continue to withhold the information that we’ve asked for,” Cantor warned.

John Stanton contributed to this report.