CHANDLER, Arizona — Democrats are worried the initial euphoria of Vice President Kamala Harris ascending to the top of the ticket this summer has fizzled out at the worst possible time.

As Harris took the stage in battleground state Arizona on Thursday for the second time in two weeks, she immediately called herself the “underdog.” It’s a word she has used often to motivate voters. This time, however, Democrats fear the sentiment reflects an uncomfortable reality that she is behind.