Sinn Fein has pulled off a stunning result in Ireland.

The outsider party, perhaps best known for its historical links with the militant Irish Republican Army, surged in the country's general elections over the weekend. Its candidates vastly outpaced expectations by winning about 24.5% of the first-preference votes to fill the 160 seats of the Dáil Éireann, Ireland's lower house of parliament.

That represents more than each of its two biggest competitors. Fine Gael, led by Prime Minister Leo Varadkar, got just under 21% of first-preference votes, while Fianna Fail won just over 22%. With more than three-quarters of parliamentary seats allocated by Monday evening local time, Sinn Fein held a substantial lead over its rivals.

That does not mean the left-wing Irish nationalist party will walk away with control over the government. No single party is likely to even come close to the 80 seats necessary for a majority, and the leaders of both Fine Gael and Fianna Fail — including Varadkar — have previously ruled out a coalition with Sinn Fein, citing the party's policies and its controversial historical connections with the violence of The Troubles.

So the split vote portends a political muddle far more than it represents a rout — but the results nonetheless mark a shocking win for Sinn Fein that will have major consequences for Ireland.

Here are a few reasons why.

1. The duopoly shows cracks

Two center-right parties, Fine Gael and Fianna Fail, have enjoyed a virtual stranglehold on Irish politics since the country gained independence from Britain roughly a century ago. Since the enactment of Ireland's constitution in 1937, every Irish prime minister, or taoiseach, has represented one of the two major parties.

It's unclear whether Varadkar's position will be endangered by the political wrangling to come. Regardless of how that shakes out, plenty of Irish voters registered their desire to shake up what had effectively become a two-party system.

"Irish people now want an alternative party for government. This isn't a protest vote," Sinn Fein leader Mary Lou McDonald told France 24. "This is an expression of deep dissatisfaction with the traditional big two parties here."

"Ideally, I'd like us to form a government that is entirely new, without the two big parties," she added, noting that Sinn Fein had begun coalition talks with other small parties, such as the Greens and Social Democrats.

Varadkar himself acknowledged that the weekend was a watershed of sorts for Irish politics.

"It seems now that we have a three-party system — three parties all getting roughly the same number of votes, the same number of seats," the prime minister told reporters Sunday. "And that is going to make forming a government quite difficult."

2. All is not well at home

On the surface — or at least to observers abroad — Varadkar had plenty of reason to feel confident as voters headed to the polls. Ireland's youngest-ever prime minister, and its first to openly identify as gay, Varadkar successfully campaigned for the repeal of the country's longtime abortion ban and has more than held his own in the bruising Brexit negotiations with Ireland's U.K. neighbors.

Yet for all the glowing headlines these wins have earned him beyond Ireland's borders, there was still plenty of domestic discontent over two issues that hit much closer to home for Irish voters: housing costs and health care.

The numbers alone can tell the story:

As for health care, hospitals in Ireland have grown so overcrowded that — according to the Irish Nurses and Midwives Organisation — it has become an "intolerable situation for vulnerable patients and frontline workers alike."

"Nobody should have to endure this in a modern health service," said the organization's general secretary, Phil Ní Sheaghdha.

"People find it a bit galling, I think, to hear this talk of a fantastic economy and how we've turned it around but then see homeless people on the streets, see their children moving back home because they can't afford to rent or to get on the property market," reporter Jennifer Bray of the Irish Times explained Saturday on Weekend Edition.

Part of Sinn Fein's success this weekend came from convincing voters that, in McDonald's words, the left-wing alternative to the two major parties could be a "vehicle for change" on matters more pressing than Brexit.

3. The past may be past

Sinn Fein's surge shocked observers not just for its present outsider status in Ireland, but also for what fostered that outsider status in the first place: the party's historical connections with the IRA.

The paramilitary organization, which tried to achieve Irish unification by violent means, was a key player in the decades-long sectarian bloodshed in Northern Ireland known as The Troubles. More than 3,500 people died in the violence.

The Good Friday peace deal of 1998 ended the violence with a power-sharing agreement in Northern Ireland. Today, Sinn Fein nationalists share the regional government there with the pro-U.K. Democratic Unionist Party.

Despite the peace, bad memories linger on both sides of the border, and Sinn Fein continues to carry the baggage of its historical association with the IRA. Hence the reluctance of Fine Gael and Fianna Fail leaders to even work with the party — though Micheál Martin, leader of Fianna Fail, appears to be relenting in his opposition since the election.

But among voters, it appears that baggage has become lighter with time.

Sinn Fein turned to McDonald as the new face of the party in 2018, moving on after 35 years under her predecessor, and campaigned on issues such as housing prices and health care rather than stressing its push for a united Ireland, the group's foundational policy issue.

The shift appeared to make a difference for younger voters, many of whom might not personally remember the Troubles. Exit polls published Saturday showed that Sinn Fein was far and away the most popular party among voters under the age of 34.

"It's not very complicated," said Donnchadh Ó Laoghaire, a Sinn Fein member who won election Sunday. "There's a whole generation of people out there who feel locked out of the possibility of ever having their own home."

"And I think," he added, "that our policies, our vision for housing, our ambition for housing has clearly connected with young people."

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