LISBON — Portugal is holding an early general election on Sunday when 10.8 million registered voters will elect 230 lawmakers to the National Assembly, the country’s parliament. The lawmakers will then choose a new government.

Two moderate parties that have alternated in power for decades — the center-left Socialist Party and the center-right Social Democratic Party — are once again expected to capture most votes.

A right-wing populist party, though, is feeding off disenchantment with the mainstream parties and could help propel Europe’s tilt to the political right.

These are the issues that have been at the heart of the campaign:

CORRUPTION SCANDALS

The election is taking place because a Socialist government collapsed in November during a corruption investigation. The scandal included a police search of Prime Minister Antonio Costa’s official residence and the arrest of his chief of staff. Mr. Costa has not been accused of any crime.

Also in recent weeks, a Lisbon court decided that a former Socialist prime minister in power 2005-2011 should stand trial for allegedly pocketing some $36.7 million during his time in office.

The Social Democratic Party has also been embarrassed by corruption allegations.

A recent graft investigation in Portugal’s Madeira Islands triggered the resignation of two prominent Social Democrat officials. The scandal erupted on the same day the Social Democratic Party unveiled an anti-corruption billboard in Lisbon that said, “It can’t go on like this.”

A 5-year-old radical right populist party called Chega, or “Enough,” has made the fight against corruption one of its political banners and could profit from the scandals.

A HOUSING CRISIS

House prices in Portugal jumped by around 80 percent and rents rose by some 30 percent between 2010 and the second quarter of last year, European Union statistics show. Those increases were far above wage rises.

Much of the price growth came in recent years, largely fueled by the influx of foreign investors and tourists seeking short-term rentals. The shift has been felt keenly at big cities such as the capital, Lisbon, where many locals have been priced out of the housing market.

The problem was made more acute by last year’s surge in mortgage rates and inflation.

LOW PAY

The Portuguese have long been among Western Europe’s lowest earners. That rankles, and the latest street protests over pay have come from police officers.

Last year, the average monthly wage before tax was around 1,500 euros, or $1,630 — barely enough to rent a one-bedroom flat in Lisbon.

The minimum wage, earned by more than 800,000 people, is 820 euros, or $893 a month. That’s 676 euros, or $736, in take-home pay. Close to 3 million Portuguese earn less than 1,000 euros, or $1,090, a month.

Weak economic growth and productivity have kept a lid on incomes. In the first 22 years of this century, average annual GDP per capita growth was around 1 percent. The economy feels stuck in a low gear.

Portugal’s gross domestic product per capita has been lower than 80 percent of the EU average since 2011, and before that it never surpassed 83 percent.

THE LEADING CANDIDATES

The Socialist leader, Pedro Nuno Santos, is a lawmaker and a former minister for housing and infrastructure.

Mr. Santos, 46, quit the previous government under a cloud over his handling of bailed-out flag carrier TAP Air Portugal and an unresolved dispute over the site of a new Lisbon airport.

He comes from a family in northern Portugal with successful business interests. When much younger, he once drove a Porsche but says he “didn’t feel comfortable” owning the car so he sold it.

The 51-year-old Social Democratic Party leader, Luis Montenegro,  is a lawyer who served as a lawmaker for 16 years after first entering Parliament at the age of 29.

He heads the Democratic Alliance, a grouping of mostly small right-of-center parties formed for the election. He has never been part of the Portuguese government.

Police investigated claims in 2017 that Mr. Montenegro received trips to soccer games paid for by a press company, but later dropped the case.

Chega leader Andre Ventura, 41, appears to have no chance of becoming prime minister but he may end up playing a key role after the election if his party’s support jumps.

Mr. Ventura has had a colorful career. He has gone from being a practicing lawyer and university professor specializing in tax law to a boisterous TV soccer pundit, an author of low-brow books and a bombastic orator on the campaign trail.