Display Screen or Portion Thereof with a Graphical User Interface

A portion of the disclosure of this patent document contains material to which a claim for copyright is made. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in the Patent and Trademark Office patent file or records, but reserves all other copyright rights whatsoever.

The FIGURE is a front view of a first embodiment of a display screen or portion thereof with a graphical user interface.

The outermost broken line represents a display section or portion thereof and forms not part of the claimed design. The dot-dashed broken lines represent a boundary of the claimed design and form no part of the claimed design. All other dashed broken lines represent features of the display screen or portion thereof with a graphical user interface that form no part of the claimed design.