Low turnout marred Lebanon’s first parliamentary poll in nine years, with voters seemingly unconvinced that a new ballot – and system of voting – could shake up a political order that has remained beholden to regional interests since the end of the civil war.

The election had been hailed as potentially a breakthrough moment for a country central to power struggles between Iran and Saudi Arabia and rattled by decades of domestic turbulence. However, by the close of polls on Sunday, less than half of registered voters (47%) had cast ballots, 5% less than the last poll in 2009 – and far below projections.

Many who did not vote said they believed the election had been predetermined by the very exiles promising change and that a new, complex electoral law intended to inject fresh voices had instead cemented the old guard.

“If I thought standing in a two-hour line to vote would change anything, I would have,” said Mohammed Obeida, a Beirut resident. “I would have taken my grandad too. He stayed home because he’s seen it all before.”

Early indications suggested that two major political blocs, the pro-western March 14 alliance, and the pro-Iran and Syria March 8, may have been diminished, a result that – if borne out – could unsettle an already fragile domestic scene that has been dominated by former warlords from the civil war era.

Both factions started as protest movements in the aftermath of the assassination of the former prime minister Rafik Hariri, and have been central to Lebanese society since. However, the new electoral law, which replaced a winner-takes-all system with proportional representation requiring a choice for a list as well as an individual candidate, is thought likely to weaken the two blocs.

March 14, which is dominated by Sunni Muslims and half the country’s Christians, appeared most at risk of fragmenting, with waning Saudi backing and growing disaffection leading some Sunnis to look for new power bases. Saad Hariri’s hold on the prime ministership is not likely to be threatened. However, ahead of the election he faced a mounting challenge from Sunni figures whose support he could have banked on earlier in his tenure.

Women queue to vote at a polling station in Beirut. Photograph: Anwar Amro/AFP/Getty Images

Hezbollah, a dominant player in Lebanon’s political landscape, had also faced dissent within its usually disciplined ranks, particularly over its ongoing involvement in Syria where up to 1,800 members have been killed supporting Bashar al-Assad. However, the militia cum political bloc appeared to have performed well in its strongholds and could emerge from the ballot with an even tighter hold on Lebanon’s affairs.

Such a result would unsettle neighbouring Israel and Saudi Arabia, which scaled back its long-term support for Hariri when Crown Prince Mohammed bin Salman summonsed him to Riyadh last November and ordered him to resign, after complaining that his government had given cover to Hezbollah – the most important arm of Iran’s foreign policy.

Hariri was eventually able to leave Riyadh, but his relationship with the Saudi leadership has remained strained, and the Saudis remained largely disengaged from the election process.

“If the Saudis stayed in this, things may have been better for the Sunnis,” said Othman Skaf, from north Lebanon. “They left because the country was being eaten by Hezbollah. But by leaving they ensured that would happen even quicker.”

Nadim Shehadi, the director of the Fares Centre for Eastern Mediterranean Studies at Tufts University in Boston, said: “The big picture is that the Sunnis being defeated regionally translated into fragmentation and crisis of leadership on the ground. This is not good because the frustration could produce more support to radicals. The alternative leadership would be more radical.”

While the election was contested largely on local issues, such as rampant corruption, a moribund economy and poor civic services, regional affairs loomed large. A raging war in Syria, the ongoing fallout from the US-led invasion of Iraq, wars against Islamic State and in Syria and the displacement of more than half of Syria’s population have fed disaffection across Lebanon.

Sunni populations have felt especially disgruntled, with senior leaders and residents claiming they are on the losing side of a regional ledger that has seen Shia Iran prosper in three countries at their expense.

Additional reporting: Nadia al-Faour