Final answer:
Since 1968, the number of political action committees (PACs) has increased, allowing organizations to support individual candidates over party slates, leading to changes in campaign dynamics and the emergence of shadow campaigns.
Step-by-step explanation:
Since 1968, there has been a rise in the number of political action committees, in which organizations form to support the individual candidate rather than the party's slate of candidates. The proliferation of these committees has changed the dynamics of running campaigns. In contrast to the past when party organizations dominated campaign management, individual candidates can now receive direct support from interest groups through PACs or candidate-aligned parties. PACs, in particular, have been influential by collecting and distributing funds to candidates aligned with their interests, often favoring incumbents or chairs and members of relevant congressional committees.
These shifts reflect a broader change in the electoral landscape, coupled with the impact of campaign finance reforms such as the McCain-Feingold Act, which attempted to regulate campaign financing but also led to the creation of new political organizations seeking to circumvent these regulations. The shadow campaign phenomenon also represents an era where third-party organizations can push a political agenda without the direct endorsement of a candidate, influencing voter perceptions through strategic advertisements.