Washington (CNN) In the end, it may come down to the tweets.

"The special counsel, Robert S. Mueller III, is scrutinizing tweets and negative statements from the president about Attorney General Jeff Sessions and the former FBI director James B. Comey, according to three people briefed on the matter."

Of all the not-normal things about Donald Trump's presidency, his use of Twitter may be the most abnormal. Twitter is Trump's sounding board, his Festivus pole ("I got a lot of problems with you people!"), his soapbox.

Trump has said flatly that without Twitter -- and the ability it gave him to speak without editing to his followers -- he might not have won anything.

Read More