WASHINGTON — Rob Porter, who resigned as President Donald Trump’s staff secretary following allegations of spousal abuse, was one of as many as two dozen senior White House officials, including the president’s son-in-law, Jared Kushner, who hold interim security clearances.

Kushner is still working without a permanent security clearance, according to an administration official familiar the process but not authorized to discuss it publicly.

Interim clearances are routinely issued — some because of a massive government backlog of hundreds of thousands of security clearance reviews.

A senior administration official said as many as two dozen senior officials don’t hold permanent clearances. The official wasn’t authorized to discuss the matter and spoke on the condition of anonymity.

Questions and answers about security clearances:

Q: How are government workers screened?

A: The government conducts background investigations to make sure that job applicants or employees are suitable for employment. The scope of the investigations is based on the kind of information the worker will handle. Those handling top-secret information are more thoroughly vetted than those who don’t handle classified information at all. A “full-field background investigation” is required for employees assigned to high-risk jobs.

Q: How does the process begin?

A: Those seeking a security clearance must complete a lengthy document, usually about 120 pages long, that queries a person’s personal and professional life. Investigators look for red flags on about 13 areas of concern: allegiance to the U.S., foreign influence, foreign preference, sexual behavior, personal conduct, financial considerations, alcohol consumption, drug involvement, psychological conditions, criminal conduct, handling of protected information, outside activities and the use of information technology

Q: Who does the investigations?

A: The FBI doesn’t do every background investigation, but often is involved in cases requiring top security clearances. FBI Director Christopher Wray said the FBI submitted a partial report on the Porter investigation in March 2017 and completed a background investigation in late July. Soon after that, the FBI received a request for a follow-up inquiry. It completed that in November and closed its background investigation in January. In early February, the FBI received additional information on the case that it passed onto the White House, according to Wray.

Q: What happens after a background investigation is completed?

A: Investigators compile a report of their findings, disclosing issues that might trigger red flags, especially regarding the 13 areas of concern. Bill Savarino, an attorney who represents clients during security clearance investigations, said the report might also include an investigator’s own observations about a person’s candor. Savarino said the report then is sent to the agency — in Porter’s case, the White House— that requested the investigation.

Q: Who decides who gets a security clearance?

A: The FBI doesn’t grant or deny clearances or make recommendations. White House press secretary Sarah Huckabee Sanders said the White House Personnel Security Office received the FBI’s information about the Porter investigation. She said that office was still in the process of making a final recommendation about issuing Porter a clearance when he resigned, raising questions about when top White House officials learned about the allegations that he abused two ex-wives.

Q: Why are interim clearances issued?

A: According to the FBI, interim security clearances are granted in “exceptional circumstances” — when someone must perform official functions before authorities can complete a full background check and decide whether to issue a full security clearance.

The FBI says, however, that when an interim clearance is granted, “the background investigation must be expedited, and, if unfavorable information is developed at any time, the interim security clearance may be withdrawn.”

National Intelligence Director Dan Coats said it’s necessary for interim security clearances to be granted “particularly in a new administration” or one with lots of turnover in personnel. But he said interim clearances should come with controlled and limited access to classified information.