Reading support:
This graph shows the expenditure of the so-called super PACs for opposing candidates in the United States up to April 23, 2012. Super PACs are independent expenditure-only committees, which may raise unlimited sums of money from corporations, unions, associations and individuals, then spend unlimited sums to overtly advocate for or against political candidates. However, direct coordination and communication between political candidates and super PACs is prohibited. Each of the GOP candidates is supported by at least one super PAC. As of April 23, super-Pacs have been spending about 19 million U.S. dollars on TV-attack ads and other matters to weaken Newt Gingrich in the race.