1. The Left is united and looking to overtake the center-left.

Podemos candidate Pablo Iglesias and IU leader Alberto Garzón have overcome resistance from some sectors of their respective parties to form an alliance that gathers virtually all the formations left of PSOE, including important regional parties in Galicia, Valencia, and Catalonia.

Unidos Podemos aims to revamp the Left’s appearance and win more votes than Podemos and its allies did in December.

However, the coalition’s main roadblock is the electoral system, an imperfect form of proportional representation. The small size of the electoral districts and the D’Hont system penalizes small parties running national elections.

For example, IU won over nine hundred thousand votes in December, but only received two parliamentary seats. Each seat cost them 460,000 votes while PP’s and PSOE’s MPs were won with around 60,000 votes and the Basque Nationalist Party (PNV) got a seat for each 50,000 votes.

Unidos Podemos therefore needs to decisively defeat PSOE in key provinces — which seems likely to happen — to take advantage of the electoral system’s proportional division of seats.

The Left’s ambitions have made the term “sorpasso” — the Italian world for “overtaking” — a buzzword in Spanish politics. If Unidos Podemos wins more votes and MPs than PSOE, the traditional social-democratic party will suffer its worst crisis ever.

Some are even predicting that Pedro Sánchez’s party will undergo “Pasokification” — another trendy term that refers to the sudden decline of Greece’s Panhellenic Socialist Movement (Pasok) after Syriza’s rise.

2. For the business interests backing it, Ciudadanos hasn’t lived up to its early promise.

Ciudadanos might qualify as one of the biggest bluffs in recent Spanish politics. All last year, pollsters trumpeted the party’s skyrocketing vote share, even predicting its electoral victory.

But in election after election, Ciudadanos, which is led by Albert Rivera, has come in fourth.

This position has allowed it to systematically support PP candidates, revealing their engagement with neoliberal policies and how vacuous their anti-corruption promises are.

The only exception has been the 2015 election in the party’s home region of Catalonia. There, Ciudadanos’s anti-independentist discourse allowed it to become the leading party in a highly fragmented regional parliament.

Different arguments have been put forth to explain polling firms’ continuous exaggeration of Ciudadanos’s electoral prospects: their voters’ lack of fidelity, the difficulty of opening political space in the center, and so on.

But maybe the real reason for the firms’ enthusiasm is that economic elites see Ciudadanos as a party able to channel the Spanish population’s unstoppable desire for change without endangering any important elements of the current political and economic system.

Ciudadanos has tried to portray itself as a center-progressive party, but its young leaders’ charm has not been enough to fool many progressive voters. In the December election it successfully attracted a large number of former PP voters, fed up with the party’s corruption.

But now that Unidos Podemos represents a “red danger” for the Right, it is likely that many of them will vote PP this time.

3. The Popular Party will likely win the election, but to form a government the Socialists will need to discredit themselves even further.

All polls predict a PP victory, citing both rural and older voters’ unshakable fidelity to the conservatives and the likely split among left-wing voters between the Socialist Party and Unidos Podemos.

It also seems clear that Unidos Podemos will win more votes than PSOE — and maybe more seats too — provided that the anti-austerity coalition manages to turn out their voters for the second election in six months and attract more former Socialist supporters.

One of the election’s main unknowns is whether the combination of PP’s and Ciudadanos’s MPs will give them a majority. This would be a hard blow for the Left, as all the energy Podemos generated in the past few years would not have been able to stop a new right-wing government.

That said, PP and Ciudadanos will probably need PSOE’s abstention to govern, an option supported by the main PSOE leaders but very few of their voters.

If PSOE chooses to support that “big coalition,” Unidos Podemos will become the only important opposition force to austerity, which would condemn PSOE to an even steeper decline.

4. Unidos Podemos is the only national party in Spain open to a referendum on the Catalan question.

One or two years ago, a referendum on Catalonia’s independence seemed a likely option. But the movement lost momentum in last May’s regional election, when the independentist parties earned fewer votes than the unionist ones.

The biggest surprise came in December when the left-wing alliance En Comù Podem (In Common, We Can) — led by Podemos and Barcelona’s mayor Ada Colau — were Catalonia’s leading party in the general election vote. They’ll probably do even better on June 26.

En Comù Podem is neither independentist nor unionist: they propose a legally binding referendum on independence, which would need the Spanish government’s approval.

The only national party defending this position is Unidos Podemos; therefore only a Pablo Iglesias–led government would accept the referendum’s results. So unless Unidos Podemos defies the odds and wins the national election today, Catalonia’s independence vote is unlikely to take place anytime soon.

5. Success for the Left in Spain would have an impact across Europe.

The June 26 election is a major milestone in the continental struggle against the European Union’s austerity measures and xenophobic policies.

The Spanish economy’s size — it is the fourth largest in the eurozone — would make it impossible for the troika to repeat its performance in Greece if faced with a Spanish left-wing government.

Also, Unidos Podemos would break the right-wing consensus about the so-called refugee crisis within the European Council: the party calls for creating legal paths for refugees’ and economic migrants’ arrival in Spain and Europe and will propose other measures opposed to the dominant European migration policies.

Europe is facing a historical crossroad. Far-right parties are getting impressive electoral results in a growing number of countries, including Austria, France, Hungary, Poland, and the traditional conservative and social-democratic parties are embracing their xenophobic platforms.

At the same time, the mass protests that have taken place all across Europe since the beginning of the crisis haven’t been able to stop the austerity policies.

In this context the electoral path is unavoidable for the European radical left. The Greek case has shown that winning an election doesn’t mean winning real power, and a Pablo Iglesias–led government would need massive popular mobilization and international support to resist the European Union and business pressure.

But a Unidos Podemos electoral success would still be a great step forward for the ensemble of European progressive and radical forces, and a source a hope across the continent.