Display Screen or a Portion Thereof with a Graphical User Interface

This application is related to the following commonly owned co-pending patent application: U.S. application Ser. No. 29/901,879, entitled “Display Screen or Portion Thereof With a Graphical User Interface,”. The sole FIGURE is a front view of a display screen or a portion thereof with a graphical user interface of my new design. The dashed broken line perimeter in the drawing illustrates a display screen or a portion thereof and forms no part of the claimed design. The remaining dashed broken lines in the drawing illustrate portions of the graphical user interface that form no part of the claimed design.