(CNN) Aides to President Donald Trump believe they have the search for the anonymous author of the New York Times op-ed that shook the political world down to a few individuals, a source close to the White House told CNN on Friday.

Trump is still "obsessed" with finding the person, though he is being counseled by White House chief of staff John Kelly to let it pass, to avoid bringing more attention to the claims in the op-ed. The opinion piece was written by an anonymous senior administration official alleging an internal resistance to the President in his own administration.

CNN is not aware of the identity of the individuals White House aides have zeroed in on. In an interview with CNN's Christiane Amanpour, White House counselor Kellyanne Conway said Trump believes the individual is someone from the national security sector of the government.

The op-ed published Wednesday afternoon, just a day after excerpts from veteran journalist Bob Woodward's new book, "Fear: Trump in the White House," were published. The book passages published in The Washington Post and by CNN showed a White House consumed by chaos and disarray, including stories of aides insulting Trump behind his back and going so far as to steal documents off his desk in order to keep him from signing them.

The anonymous writer of the op-ed said the resistance inside Trump's administration is not the same as the resistance from the political left. The author wrote that the resistance inside the government wants "the administration to succeed ... But we believe our first duty is to this country, and the president continues to act in a manner that is detrimental to the health of our republic."

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