Nearly half of the chamber’s 348 seats were up for grabs in the vote, an indirect election in which local elected officials choose the senators.
President Emmanuel Macron’s centrist movement held on to some key seats, but remains in the minority. His Republic on the Move party has lost popularity since the last election in 2017, following yellow vest protests against economic injustice and dissatisfaction with Macron’s management of the coronavirus crisis.
The Greens party had a boost in this year’s municipal elections due to growing public concern about climate change. It had just four senators in the outgoing Senate, and said by Sunday evening that it had at least 11, above the 10 needed to form a group.
Marine Le Pen’s far-right National Rally said it held onto its single Senate seat.
Senators serve six-year terms, and elections are held every three years for roughly half of the chamber.