France's second round of nationwide municipal elections handed the left a string of high-profile wins in the biggest cities, drawing battle lines for the 2027 presidential race.

As polls closed early on Monday, the left prevailed in Paris, Marseille, Lyon and Lille, while the far-right National Rally saw its hopes of a breakthrough dashed by defeats in Toulon and Nimes after leading the first round of voting in both.

The results revealed the strengths and weaknesses of France's fractious political parties a year ahead of the all-important presidential vote, analysts say.

Beyond gauging voter sentiment before 2027, when President Emmanuel Macron steps down, the results show which alliances might work nationally.

"They create momentum, provide a boost and establish a narrative," Frederic Dabi of the polling institute Ifop, was quoted as saying by The Guardian.

Most of France's roughly 35,000 local councils were settled in the first round vote last week, but tighter races, especially in big cities, came down to the second round, where electoral alliances proved decisive.

The main takeaway was that deals between the mainstream left and far-left France Unbowed party did not work, as voters moved toward the center and right in longtime Socialist Party strongholds such as Clermont-Ferrand and Brest, a BBC analysis said.

The runoffs were widely cast as a bellwether, with Paris and Marseille in the balance and both the hard left and far right hoping for gains, reported France 24.

Socialist Emmanuel Gregoire won the Paris mayoralty, in line with polls and reinforcing the capital's left-leaning profile. Right-wing contender Rachida Dati proved divisive, and her looming corruption trial likely cost her votes, the BBC reported.

"Paris has decided to stay true to its history," Gregoire said.

"Paris will be the heart of the resistance against this alliance of the right, which seeks to take away what we hold most precious and fragile: the simple joy of living together," he added.

However, Manuel Bompard, national coordinator of France Unbowed and a member of the National Assembly, pointed to the party's first-round win in Saint-Denis, a northern suburb of Paris, and its same-day victory in Roubaix.

"Tonight we have made the demonstration that nothing can stand in the way of a people on the move," he said. "Next year, the new France will sweep away the world of Macron and his nefarious policies."

National Rally, despite leading pre-presidential polls, fell short in Marseille and Toulon as opponents united.

In Nice, hard-right leader Eric Ciotti, of the Union of the Right for the Republic party, defeated incumbent Mayor Christian Estrosi, a result the National Rally hailed as proof of an emerging "new right".