Display Screen or Portion Thereof with Graphical User Interface

FIG. 1 is a front view of a first embodiment of the claimed design of a display screen or portion thereof with a graphical user interface; and,

FIG. 2 is a front view of a second embodiment of the claimed design of a display screen or portion thereof with a graphical user interface.

The outermost broken lines in the FIGURES illustrate a display screen or portion thereof and form no part of the claimed design. The fluctuating (e.g., wavy) broken line connected to/following the solid line in the charts or graphs in FIGS. 1 - 2 is a part of the claimed design despite being shown as a series of dashes or broken elements. The other broken lines in the FIGURES illustrate portions of the graphical user interface that form no part of the claimed design.

The gray filled areas in Figures 1 and 2 represent a contrast in appearance between the gray filled areas and the non-gray filled areas of the claimed designs.