None of the 15 agencies are expected to be singled out as doing an exemplary job of collecting or assessing intelligence on weapons of mass destruction.
The report from the nine-member presidential commission is expected next week.
"I don't get the impression that one agency is better than the other," said Senator John McCain, a member of the commission.
The report comes at a critical time for the Central Intelligence Agency, the Defence Intelligence Agency, the National Security Agency and others that collect, protect and analyse secrets.
All face the prospect of sweeping changes from the intelligence overhaul passed in December, including the appointment of a national intelligence director.
President George Bush's nominee, John Negroponte, has a Senate confirmation hearing next month.
"I don't get the impression that one agency is better than the other"
Senator John McCain
The new director will take over a sprawling bureaucracy, beset by infighting and fault-finding since the attacks of September 11 on the US, and botched pre-war intelligence that apparently greatly magnified the threat from Iraq.
The commission's recommendations will fall largely to Negroponte to implement.
Individuals familiar with the report, who spoke on condition of anonymity, said the commission devoted significant time to dissecting what went wrong on the Iraq intelligence, including many issues that have been examined by internal government investigators and the Senate Intelligence Committee.
The Silberman-Robb commission also examined closely the US capability to understand programmes in Libya, North Korea and Iran to produce weapons of mass destruction.
Libya has agreed to give up its efforts to develop such weapons and dismantle those it has.
Iran and North Korea remain significant hot spots for the United States. Intelligence operatives and analysts are not expected to get high praise for their efforts in those countries.
The panel consulted lawmakers on congressional oversight of the nation's intelligence apparatus and considered how intelligence information is provided to the president.
"I think questions had to be answered as to why we were so wrong about Iraq," McCain said.
Final drafts of the commission's report are being circulated among the intelligence agencies before declassification.
Historically, they have tried to use that process to keep secret some of the most embarrassing or critical details of investigative findings.