A side deal between Iran and the U.N.'s nuclear watchdog is still giving the Obama administration headaches with Congress, with one top senator calling it "absolutely astounding" that top U.S. officials have not even seen the agreement.

The "roadmap" worked out with the International Atomic Energy Agency deals with how Iran will account for its past nuclear work by Oct. 15, a condition required in the broader deal announced July 14 for Iran to receive relief from international sanctions.

Administration officials insist they don't have it and haven't seen the text, but have offered to brief lawmakers on what they know about its contents and say they are satisfied that the roadmap is sufficient to account for Iran's past nuclear work.

"Congress will be fully briefed on this agreement in classified session," Secretary of State John Kerry told the Senate Armed Services Committee on Wednesday.

But that's not enough for some lawmakers. Armed Services Committee Chairman John McCain called it "absolutely astounding" that the U.S. government would not have access to the actual roadmap.

"I don't think many of us would agree with that process," said the Arizona Republican.

In a series of contentious exchanges Tuesday and Wednesday, Kerry and Energy Secretary Ernest Moniz reconfirmed that there's no way Congress can see the deal. Both men confirmed that they have not read the actual roadmap, but instead have been briefed on their contents by IAEA officials.

"No country has access directly to the confidential agreements of the IAEA," Kerry said. "We don't get that exact ... it's not shared with the world."

Nonpartisan nuclear experts have noted that Iran's full accounting of any past nuclear weapons work is essential to establishing a baseline for international inspectors to verify the agreement, and lawmakers have insisted that it's crucial to review the original documents related to the IAEA-Iran roadmap as they consider the nuclear agreement.

Though the roadmap signed July 14 by IAEA Director General Yukiya Amano and Ali Akbar Salehi, head of the Atomic Energy Organization of Iran, was announced publicly, parts of it are secret. One secret part includes an annex dealing with the Iranian military facility at Parchin, where it's widely believed nuclear weapons work took place in the past.

Congressional leaders have demanded the administration hand over the full text, saying it's required by a law enacted in May governing review of the deal by lawmakers.