The financing of elections has also long been controversial, because private sources make up substantial amounts of campaign contributions, especially in federal elections. Voluntary public funding for candidates willing to accept spending limits was introduced in 1974 for presidential primaries and elections. The Federal Elections Commission, created in 1975 by an amendment to the Federal Election Campaign Act, has the responsibility to disclose campaign finance information, to enforce the provisions of the law such as the limits and prohibitions on contributions, and to oversee the public funding of U.S. presidential elections.