This is Sri Lanka's third parliamentary election in four years.
Some observers predict a hung parliament
The last poll in December 2001 resulted in a cohabitation government.
At the time, many said the results showed the Sri Lankan electorate desperately wanted the two main parties to work together to end the country's two-decade-long civil war.
That did not happen.
The leader of the United National Party, Ranil Wickramasinghe, was elected prime minister to work with an executive president from a rival party - herself elected in 1999 in presidential elections.
Prime Minister Wickramasinghe spearheaded a new phase of peace negotiations but he failed to include his rival President Chandrika Kumaratunga.
She complained the prime minister had jeopardised national security in his negotiations with the Tamil Tiger rebels.
In a surprise move last November the president took over the defence, interior and information ministries.
The move was legal but had the effect of crippling the prime minister's government.
He argued he could not go to peace talks with the Tamil Tiger rebels that were expected to resume last January without full control over the armed forces.
Indeed the Norwegian facilitators in the conflict said there was nothing they could do until it was clearer who was in control of the Sri Lankan government.
Months of half-hearted efforts to negotiate a compromise failed and the president dissolved parliament in February and called fresh elections.
Peace at stake
President Kumaratunga is hoping her United People's Freedom Alliance - which includes former leftist insurgents from the JVP - can form the next government so she controls both the legislature and the executive.
If the prime minister receives a fresh mandate many fear the confrontation with the president will continue.
The campaign has been shaken by the killing of a Tamil candidate
Ms Kumaratunga says constitutionally only the president can control defence matters and it is not clear if she would give the portfolio back to the prime minister's nominee.
For his part, the prime minister will interpret a victory as a clear mandate for his peace process and insist on the president backing down on the issue of defence.
The casualty in this power struggle between the president and prime minister may be the peace process.
Sri Lankans have enjoyed the longest period of peace since the war began.
A cease-fire signed in 2002 resulted in travel restrictions being lifted, hundreds of thousands of displaced people returning home and a tentative start to reconstruction work in the north-east of the island.
In 2000, on average 11 people died every day in the Sri Lankan conflict but for the last two years the guns have been silent and the body bags stopped coming.
There were cease-fire violations, especially by the Tamil Tigers who continued to recruit hundreds of child soldiers, assassinate rivals and extort money.
Concerns about democracy remain but the Tamil Tigers did begin a painful process of transforming from a group banned internationally as terrorists to a political movement.
Both main parties say they will continue with the peace process but the president has allied with the JVP whose leader strongly opposes a federal solution to the conflict.
One of the breakthroughs of the peace process was a commitment by the rebels to a federal system of power-sharing.
That sparked the international community to pledge an unprecedented sum of $4.5 billion to underwrite the process.
To complicate matters more a senior military commander of the Tamil Tigers broke away from the movement in early March saying he wanted a separate rebel administration in the east of the island.
Colonel Karuna complained that eastern Tamils had been discriminated against by the northern leadership of the organisation.
So far, neither the president, the prime minister nor the Norwegians have officially recognised this breakaway faction.
They know it would make it difficult to deal with the mainstream rebel leadership if they do.
The concern, though, is that the two factions could start fighting one another and the army might be drawn into the conflict.