The $4 Billion is for all major elections in the USA, from the Presidential race, senate, congressional and all the way down to state legisgative elections. This also includes non-canidate and non-party spending by interest groups.
The saddest point is that most of this money is spent on TV
ads where the only ones that make money are the already rich owners of the local stations or the network stockholders of some major market stations.
The conflict here is that the 1st Amendment makes it impossible - and correctly so - to regulate or limit in most ways political speech spending. The need for so much money means that those who donate with others, PAC
spending and the like controls the politicans. This means that generally, those who want more regulation of business, pollution, health care, trade, and so on, are excluded from access to the canidates. We all need to put pressure on the big contributors to publicize there legal bribery and shame them into putting that which is spent on campaign contibutions to more toward charity social programs and organizations.
Lets say we shift $2-3 billion toward programs to improve education, health care, disease research, help abused children and women, and so on - it would be a better investment for the public than into a politican.