Display Screen or Portion Thereof with Graphical User Interface

The FIGURE is a front view of the claimed design of a display screen or portion thereof with a graphical user interface.

The outermost broken lines in the FIGURE illustrate a display screen or portion thereof and form no part of the claimed design. The other broken lines in the FIGURE illustrate portions of the graphical user interface that form no part of the claimed design. It should be understood that the text depicted in the FIGURE is exemplary only, such that changing the values of the depicted numbers, words, and letters is possible with such changes intended to fall within the scope of the disclosure.