What is the biggest expense in a presidential campaign? Why do you think this expense is higher than other campaign expenses?

In a presidential campaign, the biggest expense is that of advertising. This expense is the highest because multiple ads need to be run for the campaign to be successful and a single advertisement can cost millions of dollars.

Explanation:

From among the activities involved in presidential campaigning, advertising in the most mandatory one. But having said that, it is also true that effective advertising doesn't come cheap. In order to make sure that the advertise reaches to the maximum of the population and potentially makes and impact, millions of dollars need to be spent.

During the period of election campaigning, the rates of advertising on a famous television network go past the mark of million dollars per ad. This explains why is advertising the most expensive in presidential campaigns.