President Donald Trump has been writing his State of the Union speech since December, a White House official told NBC News, and did a "pretty meaningful" edit on the plane to the World Economic Forum in Davos, Switzerland, last week.

He continued working over the weekend, writing notes and edits on paper copies, which were then transcribed into the draft by aides.

According to the official, Vice President Mike Pence, National Security Adviser H.R. McMaster, and National Economic Council Director Gary Cohn played a key role in advising the president on policy for the address, with aides Stephen Miller, Vince Haley, and Ross Worthington playing an important role in the writing of the speech. Staff Secretary Rob Porter played a key role in both.