noun
two major parties; two largest parties
Refers to the two dominant political parties in a system, often used in contexts like 二大政党制 (two-party system).
アメリカは事実上、二大政党によって政治が動いている。
In the United States, politics is effectively driven by the two major parties.
二大政
The policy differences between the two major parties became the focus of the election.