Final answer:
Around 60 percent of presidential campaign spending is devoted to TV ads, many of which have a negative tone. TV remains a significant medium for political campaigns, even with the growing influence of the Internet and social media.
Step-by-step explanation:
The question asks about the proportion of campaign spending dedicated to producing and airing televised political advertisements. Approximately 60 percent of presidential campaign spending is now devoted to television ads, with a significant portion containing a negative tone. While TV ads have historically been a central strategy for candidates since the 1950s, the rise of the Internet and social media is changing the landscape of political campaigning. Nevertheless, television advertisements still hold a substantial impact upon voters and command a major part of a campaign's budget.