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;

FIG. 2 is a front-enlarged view of a portion of the display screen or portion thereof with a graphical user interface of FIG. 1 ;

FIG. 3 is a front view of the portion of FIG. 2 to illustrate change in appearance, as further described below;

FIG. 4 is a front enlarged view of another portion of the display screen or portion thereof with a graphical user interface of FIG. 1 ; and,

FIG. 5 is a front view of the display screen or portion thereof with a graphical user interface of FIG. 1 , in which a mobile phone in evenly spaced broken lines is provided to illustrate an example environment.

The broken line showing of the mobile phone, and the text/words, numbers and otherwise images is included for the purpose of illustrating environmental features and forms no part of the claimed design.

FIGS. 2 and 3 show a transitional user interface in which a portion of the graphical user interface becomes transparent or semitransparent during the transitional sequence in order to reveal underlying subject matter that is shown in FIG. 3 in unclaimed broken lines. The appearance of the transitional user interface sequentially transitions between the images shown in FIGS. 2 and 3 . The process or period in which one image transitions to another image forms no part of the claimed design.