wave election

An election in which a political party makes major gains.

Japanese Meaning

ある政党が大幅に支持や票を伸ばし、勢力を拡大する選挙

Many analysts believe the upcoming wave election could reshape the balance of power in Congress.

多くの分析家は、来たる一党が大幅に議席を伸ばす選挙が議会の勢力図を塗り替える可能性があると見ている。

Sense（1）

An election in which a political party makes major gains.

wave elections

（ plural ）