Political parties play a visible role in Congress and in state legislatures. The party controlling a legislative chamber has certain privileges. For example, because of its numerical majority, the majority party is able to elect its chosen candidate to be Speaker of the House, one of the country's most powerful public officials. In both chambers of Congress, the majority party supplies the legislators who chair congressional committees. These positions often carry with them considerable political power. Party leadership in the legislature consists of the majority and minority leaders, as well as the whips, who help the leaders to maintain party discipline, particularly on votes the leadership deems are very important. By maintaining party discipline, the leadership aims to ensure that its members speak, as much as possible, with a united voice. Parties hold regular meetings to discuss issues, reinforce policy unity, and plan legislative action. These meetings are called party conferences or caucuses.
Occasionally independents run for office and win election. When they do, they tend to meet in Congress with the party that most closely resembles their position on issues. Two independents—Bernie Sanders of Vermont and Angus King of Maine—served in the Senate in the 2010s; both aligned themselves with Democratic Party senators in their party caucus.
In government, political parties may play both a proactive and a reactive role. When a party is in power in the legislature, it takes an active lead in shaping new legislation and setting the legislative agenda. When not in power, the party may react to the majority's proposals, requesting modifications or alternatives, but its power to have a strong influence on policy is limited. The role of a party in Congress depends greatly on its status as a majority or minority party—and also on whether it or the opposing party controls the presidency.
The party in government also exercises influence in the executive branch. Each party has a large group of individuals with policy expertise in various areas of domestic or foreign policy. Those individuals are ready to serve as the principal members of the various executive agencies when a member of the party wins election as chief executive. Once appointed by the president or governor of their party, they are in place to help implement the party's—and that leader's—agenda through the executive's power to execute the laws.