Display Screen or Portion Thereof with a Graphical User Interface

The patent or application file contains at least one drawing executed in color. Copies of this patent or patent application publication with color drawing(s) will be provided by the Office upon request and payment of the necessary fee.

FIG. 1 is a front view of a display screen or portion thereof with a graphical user interface in accordance with a first embodiment, showing our new design; and,

FIG. 2 is a front view of a second embodiment thereof.

The broken lines showing of a display screen in all views form no part of the claimed design.