2020年美国大选，共和党与民主党分别吸引了广泛的选民支持。如果仅将美国政党视作无强制约束力且松散的政治组织，美国总统选举中的党争现象就难以理解。基于此困惑，本文核心问题为：美国共和党与民主党分别如何展开组织建设？什么因素导致它们采取不同策略？为回答这一问题，本文将主要从提出问题、文献回顾、核心理论框架及案例分析几个章节展开论证。本文从总统选举与国会地位视角解释美国政党建设的策略。在美国政治中，政党建设主要包括筹集资金、建立人才队伍、招募候选人及发起项目活动等四个核心要素。面对不同的选举压力，全国政党委员会通过增加资源投入的方式资助不同州政党发展。本文采用全国政党委员会向州政党转移资金数额分布情况衡量美国政党建设的策略，这主要可分为均衡、混合与集中三种情况。当总统选举的紧迫程度较低且同时失去联邦参众两院多数席位时，美国政党建设的策略呈均衡模式；当总统选举的紧迫程度较低且控制联邦参议院或众议院多数席位时，美国政党建设的策略呈混合模式；当总统选举的紧迫程度较高且控制联邦参议院或众议院多数席位时，美国政党建设的策略呈集中模式。本文将采取四个案例验证核心假设。2013-2014年，在总统选举的紧迫程度较低且控制联邦众议院多数席位时，美国共和党的建设策略呈混合模式，共和党全国委员会优先考虑赢得2014年中期选举，并有针对性地支持不同州共和党发展。2015-2016年，在总统选举的紧迫程度较高且同时控制联邦参众两院多数席位时，美国共和党的建设策略呈集中模式，共和党全国委员会重点发展总统选举中竞争激烈地区的州共和党。2017-2018年，在总统选举的紧迫程度较低且同时失去联邦参众两院多数席位时，美国民主党建设呈均衡模式，民主党全国委员会相对均衡地资助全国范围内州政党。2019-2020年，在总统选举的紧迫程度较高且控制联邦众议院多数席位时，美国民主党的建设呈集中模式，民主党全国委员会重视总统选举事项，并重点资助竞争激烈地区的州民主党。

In the 2020 U.S. election, both the Republican and Democratic parties garnered support from diverse groups of voters. However, understanding the intense partisanship in the United States requires going beyond viewing political parties as merely loose political organizations. This paper seeks to explain how the Republican and Democratic parties initiate organizational building and what factors drive them to adopt distinct party-building strategies. To achieve this, the paper relies on a literature review, core theoretical framework, and case analysis.In this paper, the two main explanatory variables used to analyze party building strategies in the United States are presidential elections and standing in Congress. Party building in American politics involves four core elements: fundraising, talent training, candidate recruitment, and event initiation. Based on resource investment in national party committee, the specific strategy of party building is determined by disparate electoral pressure conditions. To measure the strategy of party building, this paper adopts the distribution of funds transferred from the national party committee to state parties, which can be classified into three categories: average, mixed, and concentrated patterns. When confronted with less urgency of presidential elections and minority standing in Congress, the strategy of party building tends to follow an average pattern. When confronted with less urgency of presidential elections and majority standing in the federal Senate or House of Representatives, the strategy of party building tends to follow a mixed pattern. When confronted with more urgency of presidential elections and majority standing in the federal Senate or House of Representatives, the strategy of party building tends to follow a concentrated pattern.This paper will test the core hypothesis using four cases. The first case is from 2013-2014 when the Republican party building strategy, due to less urgency of the presidential election and a majority in the federal Senate, manifested as a mixed pattern. During this time, the Republican National Committee focused on the 2014 U.S. Senate election and targeted support for state Republican party development. The second case is from 2015-2016 when the Republican party building strategy, due to more urgency of the presidential election and majority in Congress, tended to be a concentrated pattern. During this time, the Republican National Committee focused on funding the state party in battleground states. The third case is from 2017-2018 when the Democratic party building strategy, due to less urgency of the presidential election and minority in Congress, manifested as an average pattern. During this time, the Democratic National Committee developed state parties widely. The fourth case is from 2019-2020 when the Democratic party building strategy, due to the more urgency of the presidential election and majority in the House of Representatives, transformed into a concentrated pattern. During this time, the Democratic National Committee focused on funding the state party in battleground states.