Display Screen or Portion Thereof with a Graphical User Interface

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

FIG. 2 is a front view of display screen or portion thereof with a graphical user interface according to a second embodiment.

The broken lines in the figures showing the display screen or portion thereof form no part of the claimed design. The remaining broken lines showing portions of the graphical user interface form no part of the claimed design.

The shading in the upper left circular portion of the design in FIG. 2 references the color green. The shading in the upper right circular portion of the design in FIG. 2 is the color orange. The shading in the lower left corner of the design in FIG. 2 is the color blue. The shading in the lower right corner of the design in FIG. 2 is the color purple/violet.