Display screen or portion thereof with a transitional graphical user interface

[0001]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.

[0002]FIG. 1 is a front view of a first image in a sequence for a display screen or portion thereof with a transitional graphical user interface showing the claimed design;

[0003]FIG. 2 is a front view of a second image thereof;

[0004]FIG. 3 is a front view of a third image thereof; and,

[0005]FIG. 4 is a front view of a fourth image thereof.

[0006]The appearance of the transitional image sequentially transitions between the images shown in FIGS. 1-4. The process or period in which one image transitions to another image forms no part of the claimed design.

[0007]The broken lines are included for the purpose of illustrating portions of the display screen or portion thereof with a graphical user interface that form no part of the claimed design.