Portuguese prime minister António Costa's Socialist Party (PS) won Sunday's (6 October) parliamentary election - increasing from 85 to 106 lawmakers in the 230-seat parliament, but short of an outright majority.

The PS won with 36.6 percent of the votes, followed by the centre-right Social Democrats (PSD) with 27.9 percent (77 seats), the Left Bloc (19 seats) with 9.6 percent and the Communist together with the Greens with 6.4 percent (12 seats), according to results released by the interior ministry early on Monday.

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"It's clear from this election that the PS is reinforced and the allied parties consolidated their positions," Costa told cheering supporters after the elections.

The far-right political group Chega! (Enough!) got one seat in the parliament - the first time a far-right party enters Portugal's parliament since the end of Salazar's dictatorship in 1974.

The opposition conservative group CDS had their worst result since 1991, prompting the resignation of their leader Assunção Cristas.

"We face the democratic result with humility," she said.

However, Sunday's election turnout was just 54.5 percent, the lowest level for a general election since 1974.

Coalition allies

The results force Costa to find allies for a coalition government once again - aiming for a full majority of 116 seats.

After the last general election in 2015 in which the Socialists finished second, Costa convinced within two months the Communists and the Left Bloc to support a minority Socialist government called 'Geringonça' or improvised solution.

This election's result showed that the Portuguese like the political solution of 'Geringonca', Costa said on Sunday.

"Stability is essential for Portugal's international credibility and for attracting investors. The PS will strive to find solutions that ensure this stability for the entire legislature," he added.

Both the Left Bloc and the Communists said they would back the Socialists once again.

According to the leader of the Communist party, Jeronimo de Souza, "there is no obstacle for the president to appoint the prime minister and for the government to be formed and start working".

"We will determine our position depending on the PS' choices, on its budget instruments and the content of its legislative proposals," he added.

A strengthened PS has also the opportunity to partner with the People-Animals-Nature party (PAN), which won four seats (3.2 percent) up from one in 2015 - PAN has supported Costa's budget in the past.

Under the 'Geringonça' formula, economic growth in Portugal was higher than the European average in recent years – 2.4 percent in 2018 – and the unemployment rate similar to the level before the debt crisis (6.7 percent).