According to Schattschneider, what role do political parties play in Congress?

Political parties serve a crucial organizational role in Congress, as highlighted by Schattschneider. They help structure the legislative process by aligning members with similar ideologies and goals, facilitating decision-making and collaboration on policies. By offering a framework within which representatives and senators can operate, parties simplify the complex dynamics of legislative work, making it easier to establish leadership, set agendas, and mobilize support for initiatives. This organization is vital for effective governance, especially in a body as large and diverse as Congress, where individual members might otherwise struggle to coordinate their efforts.

While the other options touch on relevant aspects of political dynamics, they do not capture the primary function identified by Schattschneider. For instance, while political parties can create divisions or influence bipartisanship, their fundamental purpose in Congress is to provide a cohesive structure that promotes organization and efficiency in the legislative process.