民主體制下的利益團體，在政策制訂的過程中占有舉足輕重的角色，而且多籍由遊說的過程，影響他們偏好政策及法律的訂定。在利益團體不同遊說的途徑中，政治獻金被公認是最有效的接觸管道之一，特別是選舉時競選經費資助的多寡，可以說是測量利益團體對立法行為影響的重要指標。另一方面，自五O年代美國競選文化改變以來，連帶促使聯邦公職選舉所需的經費高漲，也使得候選人必須仰賴支持群眾及利益團體的政治捐獻以應付開支。在這些基礎之上，本文旨在探討美國國會選舉過程中，候選人吸引不同類型利益團體政治行動委員會(political action committees, PACs)捐助的因素，舉凡不同 候選人的政黨、意識型態、擔任委員會主席、擔任眾議員的屆數、性別、種族與年齡等，均是我們探究的焦點。此外，由於政治行動委員會的捐款呈現所謂「設限」( censored)資料的特殊型態，我們採To-bit迴歸模型加以分析。

Interest groups in the democracy have been playing an important role in policy making. The most influential way to impact the public policy and law making is lobbying the congress. Of all different tactics of lobbying, money donation, especially the campaign contribution, is recognized the most effective approach. Because of the changes in campaign techniques and process since 1950's, it requires more money to support the campaign expenditures. Candidates therefore rely intensely on the donations from their supporters and interest groups. Based on the importance of campaign donations, this paper focuses on how Congressmen candidates attract mo-ney from different Political Action Committee (PAC). In particular, we explore the influence of candidates' party affiliation, ideology, committee setting, seniority, gender, race and age. Since PAC's contribution is characterized as the censored data, we use Tobit model for the analysis.