Portuguese voters go to the polls Sunday, two years earlier than scheduled, after a political crisis over a blocked spending bill brought down the minority Socialist government and triggered a snap election.

The Socialist Party has been in power since 2015, with Portugal one of only a half-dozen European countries having a left-of-center government. It faces a strong challenge from the center-right Social Democratic Party, its traditional rival.

Some 10.8 million voters are eligible to choose 230 lawmakers in the Republican Assembly, Portugal’s parliament, where political parties then decide who forms a government.

Here’s a look at what’s happening:

Why have an early election? Parliament last November rejected the Socialist government’s spending plan for 2022.

In previous years, the Socialists had relied on the support of their left-of-center sympathizers in parliament — the Left Bloc and the Portuguese Communist Party — to ensure the state budget had enough votes to pass.

But this time their differences, especially over health spending and workers’ rights, were too hard to bridge, and Socialist Prime Minister António Costa was left short of votes to pass his party’s plan.

Portugal’s president, Marcelo Rebelo de Sousa, said the 2022 budget is “crucial,” because it needs to relaunch the economy after the pandemic. He called a snap election so the Portuguese can decide what path the country should take.

What’s at stake? Portugal is poised to begin deploying some $50 billion of aid from the European Union to help fire up the economy post-pandemic.

Two-thirds of that sum is meant for public projects, such as major infrastructure, giving the next government a huge windfall to spend. The rest is to help selected private sector projects.

The 2022 state budget forecast GDP growth of 5.5% this year, one of the highest among countries that use the euro currency, with a jobless rate of around 6.5% — roughly the same as now.

The new government will be sworn in for a four-year term.

What are the choices? The Socialist Party is promising to increase the minimum monthly salary, earned by more than 800,000 people, to $1,021 by 2026. It is currently $800. Low wages are a common grievance among voters.

The Socialists also want to “start a national conversation” about cutting the working week to four days, from five.

The Social Democratic Party is promising income tax cuts and more help for private companies. Party leader Rui Rio wants to cut corporate tax from the current 21% to 17% by 2024.

Those two parties traditionally collect around 70% of the vote.

The Portuguese Communist Party and the Left Bloc are potential allies for the Socialists. The conservative Popular Party has in the past allied with the Social Democratic Party.

Several other smaller parties are presenting candidates nationwide and could become kingmakers by supporting a minority government.

They range from the populist Chega! (Enough!), which opposes large-scale immigration and demands more support for the police, to the People-Animals-Nature party which wants tougher animal welfare protection and tighter environmental controls.

Who’s favored to win? Opinion polls suggest a close race between the Socialists and Social Democrats. That likely means the ballot will produce another vulnerable minority government and a rocky period of horse-trading for parliamentary votes before a budget can be passed.

The Socialists, smarting from the collapse of their outgoing government, say they no longer trust their allies on the left.

The Social Democrats, meanwhile, may have to address a surge in support for the Chega! populists, whose policies they find distasteful.

Has the pandemic affected the ballot? More than a million eligible voters could be in home confinement on election day, authorities say, and officials have struggled to reconcile the constitutional right to vote with their duty to protect public health.

The highly contagious omicron variant has brought record daily infections of over 50,000 recently, compared with fewer than 1,000 in November. Portugal’s high vaccination rate of 89% of the population has largely safeguarded the health system, officials say.

The main parties shunned their traditional flag-waving campaign rallies to avoid large gatherings. Party leaders attended 36 live television debates in the first half of January — many more than usual.

Thousands of poll workers got a booster shot ahead of the ballot.

Early voting possibilities were extended, and infected people are exceptionally allowed to leave isolation to vote, with the government recommending they cast their ballot in the slower evening period.