Super PACs dominate TV advertising in run-up to presidential election

Advertising is a big part of campaigning in US political contests, and this election is no exception. The money spent by the US presidential candidates and like-minded support committees on TV advertising exceeds $6 billion. Much of this money has poured in from outside groups known as Super PACs. Thanks to a landmark Supreme Court ruling, these groups can raise and spend as much as they like to influence elections, so long as they don't coordinate directly with a candidate.