Agents would be permitted to use tactics only allowed in criminal cases: physical surveillance, recruitment of sources and "pretext interviews" - where the real purpose would not be revealed.
Justice Department and FBI senior officials briefed reporters on the draft guidelines, but would not be quoted by name because they were discussing proposals that are still likely to be changed.
Some Democratic senators and civil liberties groups have said the proposals would allow Americans to be targeted in part by their race, ethnicity or religion - and be spied on without any other basis for suspicion.
The American Civil Liberties Union, which was briefed by the FBI and Justice Department, quickly criticized the new guidelines. The rewritten rules would "give the FBI the ability to begin surveillance without factual evidence, stating that a generalized 'threat' is enough to use certain techniques," the group said.
"Also under the new guidelines, a person's race or ethnic background could be used as a factor in opening an investigation, a move the ACLU believes will institute racial profiling as a matter of policy."
The administration officials acknowledged those factors could play a role in national security and foreign intelligence cases. But they said they can already be considered under 2003 rules that are not changing.
According to the officials, the surveillance, recruitment and interview rules are too restrictive in allowing the FBI to become a post-Sept. 11 intelligence agency that can stop terrorists before they strike.
FBI Director Robert Mueller will testify about the guidelines in Congress next week.
Commenting on the decision to leave the 2003 guidelines on race, religion and ethnicity unchanged, Justice Department spokesman Brian Roehrkasse said, apart from the briefing, "It is simply not responsible to say that race may never be taken into account when conducting an investigation. The reality is that a number of criminal and terror groups have very strong ethnic associations."
He said the bureau cannot ignore La Cosa Nostra's Italian membership or that Hezbollah is largely Lebanese, "any more than it could ignore the identification of a bank robber as a short white male."
Existing guidelines do not allow an investigation based on factors like race alone; there must be some other evidence of a threat or crime, the senior officials said at the briefing.
The officials said they want the guidelines to take effect Oct. 1.
They described a threat assessment as an information-gathering tool - usually based on a tip or a news story - to determine whether a problem exists. An example would be learning whether Iranian agents are operating in a U.S. location to obtain technology secrets.
However, the assessment guidelines are important, because the threat assessment could trigger a formal investigation of Americans in foreign intelligence and national security matters.
The guidelines require that FBI agents use the least intrusive methods in their assessment. However, they would be able to work on the assessment - such as conducting Internet searches - without high-level approval from supervisors.