Washington (CNN) The White House has a list of 12 people whom they believe could have anonymously penned the explosive New York Times op-ed, an outside adviser told the newspaper Thursday night.

The op-ed, written by a senior Trump administration official, bashed the President as amoral and claimed there is a "resistance" within the administration. The essay has enraged Trump and touched off a furious search inside the administration for its author.

Republican Sen. Rand Paul of Kentucky told reporters Thursday that he thinks any White House employee with a security clearance should undergo a lie detector test to determine who wrote it.

Advisers to President Donald Trump entertained the idea, briefly discussing it among themselves, according to the Times.

The newspaper also reported that people close to Trump floated another option -- forcing senior officials to sign sworn affidavits that could be used in court if necessary.

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