Madrid, Spain - Spanish politics tentatively teetered into a new era of coalition-based governments on Tuesday, as Socialist Party leader Pedro Sanchez won a parliamentary vote of confidence by an historic two-vote margin.

Thanks to support from seven parties and, crucially, the abstention of the Catalan nationalist ERC party, the vote in favour of Sanchez's new government ended a period of prolonged political deadlock which had culminated in nearly 10 months of a caretaker government, along with two elections last year and a budget that remains broadly unchanged since 2016.

The Socialists are currently the largest political party in Spain's parliament, but in both recent elections, they fell far short of an absolute majority.

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Instead, Sanchez's new minority government of the Socialists and the left-wing Podemos grouping, itself an alliance of parties, is the first coalition in Spain at a national level since the return of democracy in the late 1970s.

The vote of confidence in Sanchez also marks the first time in Spain's recent history that a political formation to the left of the Socialists will form part of Madrid's government.

"This coalition is testament to the ongoing plurality of Spanish society," Manuel Lopez, professor of history at Spain's Open University, told Al Jazeera. "Politically, Spain can no longer be channelled into the two-party system that dominated this country's public institutions in the 1980s and 1990s.

"It's also a reflection of what's increasingly happening across Europe, where there are more and more coalitions in power who try to reflect the plurality of their societies as well."

The coalition government also ends what Lopez describes as "five years of political deadlock, since the European elections of 2014" - when a number of new parties, including Podemos, emerged on the Spanish political scene.

"Since then certain de facto power groups have been trying to put the genie back in the bottle," said Lopez. "This new coalition government shows that in fact, they can't."

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As a minority government with just 155 seats in a 350-seat parliament, and with Catalonia's ERC conditioning their neutrality on the creation of a new permanent commission to decide a road-map for their region's political future, the left-wing coalition looks set for a tumultuous time in office.

"It will be an unstable government, at least at first," Jaime Aja, professor of sociology at the University of Cordoba, told Al Jazeera. "Had the Socialists formed this alliance with Podemos before November's elections, they would have had much more room for manoeuvre.

"It'll now depend on the goodwill of left-leaning nationalist parties, as well as more conservative formations like the Basque Nationalist Party. If the current predictions of a looming economic crisis prove correct, I don't think this government will last very long."

As for the ground-breaking coalition between two left-wing groups, "it's new at a national level", Aja says, "but these kinds of alliances have often happened in regional governments or in city councils".

"The main practical effect is, arguably, to provide the most left-leaning part of the Socialist Party with a real boost. But for all that Spain's right have been sounding the alarm, the government isn't aiming at earth-shattering political changes."

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Podemos is tipped to secure four ministerial positions, with party leader Pablo Iglesias set to be one of three deputy prime ministers.

Top economic priorities for the new government include raising the minimum wage and pensions as part of labour reforms and heavier taxes on Spain's super-rich. A long-awaited climate change law is also a target.

But such is the fragility of Sanchez's majority, most legislation will likely require negotiation on a case-by-case basis with other parties.

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As for how much effect the Socialists' deal with Catalan nationalists will have; "It will certainly be important for questions like getting the budget through parliament", Germa Capdevila, a political analyst with naciodigital.cat told Al Jazeera.

"But a vote of no-confidence, like the one that saw [former PM] Mariano Rajoy lose power a few years back, is not feasible - it would need [hard-right] Vox to ally with [hard-line Basque Nationalist] Bildu, and that's not going to happen."

And the ERC? "To borrow a term from boxing... they're in a clinch position," said Capdevila. "Which means hugging your adversary briefly, to have a break and regain strength. But eventually the struggle will resume - the ERC and Socialists might be close now, but politically, their positions remain far apart."