Reading support:
This graph shows the expenditure of the so-called super PACs in supporting their candidate 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. Even though Mitt Romney is the front runner in the primaries, his opponents have received more support by super PACs up until April 23. He was supported with about 3 million U.S. dollars, which is less than his opponent Ron Paul has received (about 4.5 million U.S. dollars).