Italian Prime Minister Giorgia Meloni is set for her first regional election loss since winning power in 2022 after a centre-left candidate appeared to have won the vote for the president of Sardinia, partial results showed on Tuesday.

With almost all the votes counted, Alessandra Todde, a member of the left-leaning 5-Star Movement who was backed by the Democratic Party (PD), had 45.3% of the vote. That edged out Paolo Truzzu, a rightist candidate handpicked by Meloni, who had 45.0%.

Despite the narrow margin and the count not being totally completed, pollsters and newspapers called the result for Todde, who celebrated victory alongside 5-Star leader and former Prime Minister Giuseppe Conte and Elly Schlein, head of the largest opposition group, the centre-left Democratic Party (PD).

Todde is set to be the first woman president of the island and the first president of any region from the 5-Star Movement.

A confirmed victory would also mark the first time that the centre-left has managed to flip a region since 2015 and the result will be a boost for opposition parties after years of ballot-box beatings.

Speaking in the Sardinian capital of Cagliari, Todde told reporters she was "very happy and very proud," adding that a "page of history" was being written for Sardinia.

The vote was held on Sunday, but counting only started on Monday morning and took an unusually long time, with regional authorities waiving a 12-hour deadline for the completion of the procedure.

Meloni's bloc, including her Brothers of Italy party, the League and Forza Italia, won all four regional elections held in 2023 and until Sunday controlled 14 of Italy's 20 regions. Polls show the rightist coalition still leads at a national level.

"The wind has changed," said PD leader Schlein after she and Conte managed to bury their frequent differences to form a united front for the election.

Their regional win will put pressure on them to work more closely together if they want to overtake the right nationwide.

Sardinia, one of Italy's two main islands, has around 1.44 million adult residents. The turnout was estimated at 52.4%.

Todde, a former industry undersecretary, will replace Christian Solinas who did not run for re-election due to low approval ratings.

The next key political tests in Italy will be a March 10 election in the Abruzzo region where the PD and 5-Star have again joined forces, and European Parliament elections in June.

Meloni's Brothers of Italy is leading national opinion polls at around 28%, while the PD has about 20% and 5-Star 16%. (Additional reporting by Gavin Jones; editing by Crispian Balmer and Edwina Gibbs)