Washington (CNN) Nearly a year into President Donald Trump's administration, senior-level staffers -- including Ivanka Trump, Jared Kushner and Rob Porter -- remained on interim clearances even as other senior advisers were granted full security access, according to information obtained by CNN from a US government official.

Having interim clearance can hamper a staffer's ability to perform essential functions of the job, a former administration official said. It requires those with full permanent clearances to remain vigilant about what information is shared with those still operating on an interim basis.

There were more than 100 staffers in the Executive Office of the President who were operating on interim clearances more than a year after Trump was elected, according to the information.

It's not clear which of those staffers gained full clearances in the three months since the information was produced in November. It is also unclear whether the delay is the result of a bureaucratic backlog or potential complications in the background of these aides.

At least two dozen of the staffers with interim clearances started working on the first day of the Trump administration, according to the information.

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