Matteo Salvini, the leader of Italy’s far-right League party, has failed to overturn decades of leftwing rule in the northern region of Emilia-Romagna in an election that brought relief to the embattled centre-left.

With 98% of the ballots counted, the incumbent Democratic party (PD) governor Stefano Bonaccini had won 51.4% of the vote compared to 43.7% for Lucia Borgonzoni, the candidate backed by the League and its allies, interior ministry data showed.

Salvini had campaigned relentlessly in the region since the start of the year, seeking a shock victory that he hoped would bring down the national government, which includes the PD and is riven by internal strife.

“The ruling majority comes out [of the regional elections] stronger,” said the PD leader, Nicola Zingaretti, adding that Salvini had failed in his attempt to “shove the government out”.

A coalition led by the League did secure a resounding victory in a separate election in the southern region of Calabria, with the group’s candidate forecast to take more than 50% of the vote.

The Five Star Movement (M5S) – the party ruling nationally alongside the PD and which until two years ago was the biggest in Italy – has suffered a brutal defeat in both regions, scoring 3.5% in Emilia-Romagna and 7.5% in Calabria.

The League’s defeat in Emilia-Romagna, which has been governed by the left in various guises since the end of the second world war, is a massive setback for Salvini, the former deputy prime minister who turned the elections into a referendum on the fragile national coalition between the PD and M5S as he plots a return to power.

Salvini had threatened to send an eviction notice to the government if his coalition, which includes Brothers of Italy and Forza Italia, prevailed on Sunday. A more subdued Salvini told reporters in the early hours of Monday that he was proud of his group’s performance in Emilia-Romagna, adding that “for the first time in 70 years, there was a match”.

The PD and M5S formed an alliance after the League was ejected from government in September 2019 following Salvini’s failed attempt to force snap elections. But M5S has been beset by turmoil with more than 20 of its MPs either absconding or being kicked out since then, and Luigi Di Maio resigning as leader last week. Support for PD and M5S has waned since the two came together, with the PD polling at 18% and M5S at 16%. The League has maintained a steady lead in national polls at about 33%, while support for Brothers of Italy has risen to 10.9% in recent months.

“The coalition will go ahead but the path remains a very difficult one,” said Wolfango Piccoli, the co-president of the London-based research company Teneo Holdings. “I don’t expect any particular improvement in terms of the effectiveness of the government, especially when more and more responsibility will be on the shoulders of the PD after the M5S’s defeats.”

Voter turnout in Emilia-Romagna was almost double that of 2014, when Bonaccini won his first mandate, and may have been boosted by the Sardines, a movement against the far right that emerged in Bologna in November and has since spread across Italy. Salvini campaigned vigorously across the region since the League and its allies scored their last major victory in Umbria, a former leftwing stronghold, in late October 2019.

“I suspect that the Sardines, more than anything else, took votes away from M5S,” said Piccoli. “But in some ways, Salvini is equally responsible for the success and failure of this campaign – maybe by being present everywhere and every day he pushed a lot of people who were otherwise on the fence to vote against him.”