From Mark Blyth's 2002 book, Great Transformations:
In 1971 Congress enacted the Campaign Finance Reform Act. This Act sought to increase transparency over the electoral funding process by limiting corporate, union and private contributions. ... The most significant exception, however, was a provision to allow the 'solicitation of contributions to a separate segregated fund to be utilized for political purposes by a corporation or a labor organization' - a political action committee, or PAC.
Beginning in 1978, in response to criticism from pro-market figures such as William Simon and Ronald Reagan, corporate PACs began to shift resources from incumbents to challengers with a clear free-market bias. In September 1978, Democrats received over half of the available PAC funding. Just one month later, after the interventions of Simon, Reagan and others, Democratic incumbents received only 29 percent of total PAC resources. Business was learning to spend as a class, and interclass coordination was reinforced by PAC regulations themselves.
Since each PAC was limited to $5,000.00, rather than focusing on marginal changes to benefit individual firms, business increasingly spent as a block. To accomplish this, business developed specific clearinghouse PACs designed to maximise business's leverage, and the institutions used to do this were the newly invigorated NAM [National Association of Manufacturers], ACC [American Chamber of Commerce] and BRT [the Business Roundtable]. ... However, if business wanted to win the debate over the role and function of business within modern American life, it had to recast the actual terms of that debate. Critical in doing so were three business foundations that provided both the capital and the institutional contacts in universities and the media to develop and deploy alternative economic ideas. The Smith Richardson Foundation, the Scaife Funds, and the Olin Foundation were the prime movers in mounting an intellectual counterattack against embedded liberalism. These funds bankrolled, in whole or in part, a substantial number of policy institutes and think tanks that were explicitly designed to promote free-market and anti-embedded liberal ideas.
PS: We have a two part interview with Mark on the politics of austerity here and here.
 Blyth, Mark, 2002. Great transformations: Economic ideas and institutional change in the twentieth century. Cambridge University Press, pp.154-6.