VOA reported on "... the practice of allowing staff without security clearances to work in and around the Oval Office. Porter had only an interim clearance while holding one of the most sensitive jobs in the White House, where he controlled the flow of information to the president. A full clearance had been held up while the FBI investigated abuse allegations by his two former wives."
My recollection from the dim mists of antiquity was that the protocol was that if the clearance was not approved in a timely manner, then it wasn't going to be approved, and it was expected that the person of interest would go away, without the job, but without the blemish of having a clearance denied
it seemed to me that anyone who was still interim after a year [eg, Jared, etc] was never going to get a clearance, and had substantial derogatory information against them that would prevent them from getting a clearance.
We are also told that there are upwards of three dozen other folks at the White House who are also on "interim" status - this is a non-trivial fraction of the entire political appointee inventory at the Executive Office.
Looking a bit closer at this matter, part of the Porter matter related to his potential vulnerability to blackmail by a hostile foreign intelligence service, and presumably some fraction of the other dozens of "interims" are also vulnerable. And presumably a competent hostile spook outfit could figure this out.
Some folks are walk-ins, but others require a bit of recruitment. A "friendly" chat with one of the interims, letting them known that their secrets are safe, as long as they play along, is a good place to start.