I. INTRODUCTION Since a congressional leadership system, Majority and Minority Leaders, was put into practice, the US is proud of it and believes that the idea has brought a strong party management, unity, royalty, high levels of party voting, and professional politicians in the US political climate (Davidson 1998, 36; Patterson 1989, 395). It strengthens check and balance system between the ruling party and opposition party in the parliament. Minority Leader has a special right specified in the House rule book and responsibility defined by the party line, which would imply that he or she would engage directly with Majority counterpart to make certain important decisions. Furthermore, Minority Leader has ability to influence the outcome of the law-making process by designing the form and content of legislation in the committee and on the House floor (Steven 2007, 45). The power to set the agenda is an important type of its influence as well. In Cambodia, this kind of effective legislative leadership system is still far away from the US context. The future of US-style floor leader in Cambodia parliament remains uncertain because the parliament is weak and influenced by the government. Moreover, the check and balance system is less effective (Tsekpo and Hudson 2009) because the parliament is afflicted with the cancer of nepotism, internal corruption, and ignorance. The country’s politicians use the culture of violence and accusation to deal with each other instead of peaceful negotiation. Anyway, not all, at least some certain problems are supposed to be settled by the adoption of US-style floor leader in Cambodian parliament. This idea is initiated by Sam Rainsy, the biggest opposition leader in Cambodia, in a hope that it would create the culture of dialogue instead of accusation and violence in this post-conflict country. To do that, Cambodia has to look at the experience from the US. There are well-established literatures on institutional learning with the inclusion of policy transfer (Bennett 1997; Dolowitz and Marsh 2000) and lesson drawing (Rose 2005). In this case, we can say that this paper tends to be a lesson drawing, rather policy transfer, where the opposition party studies the development and role of the floor leaders in US systems and evaluate its potential applicability in Cambodia, resulting in the transfer of ideas, concepts and behaviours. This paper is intended to define the meaning of legislative floor leader in the context of US House of Representative and examine its concept and role. Second, it illustrates the application of this system in a case of Cambodia’s Assembly. Finally, we would like to indicate some possible impacts and limitations in applying the system to Cambodian context. II. MINORITY LEADER IN US HOUSE OF REPRESENTATIVE The official roles of the party floor leaders are not stated in the US Constitution, but they have been practiced through tradition and custom since the early 19th century (US Senate 2015). No one agrees on a specific point of time when the first floor leaders emerged officially, but it is more necessary to learn that in mid-18th century, there was a series of serious caucus conflict within the Republic party over a candidacy for the House Speaker (Nelson 1976, 19). For example, there were 7 of the 14 floor leader elections in which more than 20 different candidates competed for the position in 1834 (Nelson 1976, 17). Thus, it is widely accepted that the floor leader position was established to avoid internal party disunity (Nelson 1976, 18), and difficulty in selecting the party’s potential lawmakers as a leader in the House. Before each new session of the House of Representatives begins, two congressional parties are organized separately – House Democrats and House Republicans (Steven, Robert and Wielen 2006, 153). Both Majority and Minority Leaders are elected every two years in a secret ballot from their respective party members during the party conference to represent them on the House floor. Majority Leader helps schedule the party legislative program and direct management for all House committees. He or she is a party leader on the floor, usually the second powerful person after the House Speaker. While Minority Leader speaks for its policies and work for the interest and protect the rights of the Minority party (US House of Representation 2014). The former New York representative, Bertrand Snell, described the job of Minority Leader as a party spokesman who was supposed to criticize the policies of the majority party in a constructive way and pay close attention to all proposed laws (US House of Representation 2014). Later on, other responsibilities have been added, involving an institutional and party functions. First, the institutional rights are specified in the House rule book, allowing Minority Leader to check and balance with Majority Leaders. For example, Rule II, clause 6 provides that the Inspector General shall be appointed wi