Display Screen or Portion Thereof with Transitional Graphical User Interface

FIG. 1 is a front view of a display screen or portion thereof with transitional graphical user interface showing a first image of the claimed design;

FIG. 2 is a second image thereof;

FIG. 3 is a supplemental view of FIG. 1 , shown with unclaimed images, text, and graphical portions of the transitional graphical user interface removed for clarity in illustrating the claimed subject matter; and,

FIG. 4 is a supplemental view of FIG. 2 , shown with unclaimed images, text, and graphical portions of the transitional graphical user interface removed for clarity in illustrating the claimed subject matter.

The claim is directed toward the elements shown in solid gray tone in FIG. 1 and in solid white in FIG. 2 . The stippled-shading and the evenly spaced broken lines immediately adjacent to the stippled shading show portions of the transitional graphical user interface that form no part of the claimed design. The dot-dash broken lines in the drawings show a display screen or portion thereof and a boundary of the claimed design, and form no part of the claimed design. The remaining broken lines in the drawings, including the evenly spaced broken lines showing an electronic device and the lined-through text, graphics, and other elements of the transitional graphical user interface, form no part of the claimed design.