在選民投票行為研究中長期存在著一個爭議，那就是政黨或候選人在競選期間的競選行為，對選民投票抉擇的影響力如何？美國1940年代至70年代間的選民投票行為研究發現，競選行為對選民的投票抉擇並沒有顯著的影響力，選民的政黨認同及其所屬的社經地位，才是影響選民投票行為的關鍵因素。因為，絕大多數選民對選舉議題或候選人了解有限，而傾向根據政黨認同或執政表現等，較可信賴的資訊來作投票決定，並且競選期間不同陣營提供不同的訊息，導致競選行為對選民傳播的效應相互抵銷。但是，晚近的經驗研究發現，隨著選民政黨認同的衰退，以及選民人際溝通網絡的中立化，候選人評價和政見主張成為影響選民投票抉擇的重要變項，而重新開啟對競選行為研究的重視。

A persistent argument in political science is that party/candidates' election campaigns do not have strong effects. Because most people (1) are not care political information about issues and candidates, (2) tend to vote by party identity and government performance, and (3) face balanced information environments, (4) personal communication mediates the influence of mass communication on individual voters. But recently empirical studies find that (1) voters party identity is decline, (2) personal communication environment is heterogeneous or neutral, and (3) issue/candidate factors have strong effects on voters decision making. The main purpose of this paper is to find necessary conditions of an effective election campaign.