New Zealand Prime Minister Helen Clark has announced that the country will hold general elections on 17 September.
Ms Clark is seeking a third successive three-year term for her Labour-led administration.
Helen Clark is slightly behind Mr Brash in opinion polls
Two months of campaigning are expected to focus on the economy, New Zealand's relations with Washington, and the country's 20-year non-nuclear policy.
Recent opinion polls have put the main opposition National Party slightly ahead of the ruling party.
Ms Clark called the elections just a week before she was obliged to set a date. Analysts say she was buying time in an attempt to reverse a swing against her in the polls.
The election will pit Ms Clark, who has criticised the US decision to go to war in Iraq, against National Party leader Don Brash who has pledged to mend ties with Washington.
"Our government took a principled decision not to support a war which was wrong," Ms Clark told reporters a few days ago.
"National would have committed combat troops, and it would do so now given the chance."
Mr Brash has also said that he could, in the future, review New Zealand's 1985 ban on nuclear weapons and nuclear-powered ships.
Regarding the economy, Mr Brash has promised tax cuts if he wins power, whilst Ms Clark has promised to keep building on New Zealand's economic strength and to raise living standards.