The day John Kelly and Corey Lewandowski squared off outside the Oval Office

An argument last February between the White House chief of staff, John F. Kelly, and Corey Lewandowski, an informal adviser to President Trump, turned into a physical altercation that required Secret Service intervention just outside the Oval Office, according to a half-dozen people familiar with the events.

The episode, details of which have not been previously reported, is the latest illustration of the often chaotic atmosphere Mr. Trump is willing to tolerate in the White House as well as a reflection of the degree to which Mr. Kelly’s temper can be provoked.

The near brawl — during which Mr. Kelly grabbed Mr. Lewandowski by the collar and tried to have him ejected from the West Wing — came at a time when the chief of staff was facing uncertainty about how long Mr. Trump would keep him in his job. A guessing game over his departure has colored his tenure ever since.