Display Screen or Portion Thereof with Graphical User Interface

The FIGURE is a front view of a display screen or portion thereof with a graphical user interface showing our new design. The outer perimeter shown in a pair of broken lines in the drawing illustrates a display screen or portion thereof and forms no part of the claimed design. The remaining broken lines in the drawing illustrate portions of the graphical user interface that form no part of the claimed design. The dot-dash broken lines define boundaries of the claimed design and form no part thereof.