The party could come to power thanks to its unlikely alliance with Michel Aoun, a leader of Lebanon’s Christian minority, whose followers have joined forces with the hardline Shia Muslim party after falling out with fellow Christians.
Mr Aoun’s party is expected to secure around 30 seats, while Hezbollah, which is allied with the Amal party, another hardline Shia faction, is expected to retain its current holding of 35 seats. With around 65 seats between them, the alliance would have a slender majority in the 124 seat parliament.
Electoral success would aggravate existing tensions with Lebanon’s southern neighbour Israel, with whom Hezbollah guerrillas fought a 34-day war in 2006 after capturing two Israeli soldiers. It would also pose a serious challenge to the West’s influence in Lebanon, and threaten hopes of a new peace process between Israel and the Palestinians.
Because America lists Hizbollah as a terrorist organisation, US military support for the Lebanese army is also likely to end if the Shia party takes power. After the 2006 war, Washington had wanted to build up the Lebanese military in the hope of eventually compelling Hizbollah to disarm, but diplomats said funding would stop were Hizbollah officials to take charge of the defence ministry.
“If Hizbollah were to take the key security ministries of Defence or Interior I believe it would be illegal for America to continue funding the army,” a senior Western diplomat told The Sunday Telegraph.
The practical effects of an election victory by Hezbollah and its allies would be limited because the party already has seats in parliament and an important role in the Lebanese cabinet, which distributes power between Lebanon’s Christians and Shia and Sunni Muslims. Any new government would almost certainly preserve a “blocking minority” for the opposition.
But a victory would be symbolically important, especially for neighbouring Sunni Arab states, who are concerned about the growing influence of Iran’s Shia theocracy throughout the region.
“If Lebanon moves closer to Iran there is a much greater risk of a war soon with Israel,” said Paul Salem, director of the Carnegie Middle East Centre.
Israel’s defence minister Ehud Barak warned last week that a Hizbollah election victory would put Lebanon at risk of a much wider campaign of bombing were hostilities to break out again. Rather than just Hizbollah strongholds, the whole country would be considered legitimate target territory, he said.
British diplomats broke ranks with their American counterparts in March by indicating a willingness to talk to the party’s MPs, but not its armed wing. Hizbollah itself makes no distinction between its political and military elements.
Israel plans to hold large-scale military manoeuvres near its northern border with Lebanon on Sunday, in what was seen as a clear warning to its northern neighbour.
Nawaf Mousawi, a senior Hizbollah official running for parliament for the first time, said that the group was determined to defend Lebanon against Israeli attack.
“We know Arab armies are not capable of confronting Israel if fighting in a conventional way. But in Lebanon we now have a successful example called the resistance, which stopped Israel’s invasion in 2006,” he said.
Wider international cooperation with Lebanon, such as loans from the International Monetary Fund, could also be jeopardized if Hizbollah’s coalition wins a majority.