small political party
Refers to a political party with relatively few members or limited influence, often contrasted with major parties.
A small political party joined the coalition government.
In the election, small political parties also fielded their own candidates.
大政党 means 'major political party', the opposite of 小政党.
Compound of 小 (small) + 政党 (political party). A straightforward modern term with no obscure historical derivation.