Arlene Foster has urged unionists to turn out and vote, warning that if Sinn Fein emerges on top in local government elections it will strengthen calls for a border poll.
The Democratic Unionist Party leader said “every vote counts”.
“Some claim it does not matter which party you vote for, but you can be absolutely certain that it would be heralded as a massive success for republicans and a massive defeat for unionism if unionism was to be split and republicans were to have a massive win, and use the election results to strengthen their demand for a border poll,” she added.
Mrs Foster was speaking as her party launched a 40-page manifesto for the local elections on May 2.
Many of her party’s candidates attended the official launch event at Kingspan Stadium in east Belfast.
Mrs Foster continued: “We believe in strong unionist co-operation and that is why this party encourages people, after giving their preference for DUP candidates, to further transfer to other pro-union candidates in the election.
“We all know in our hearts that unionism can’t afford to be divided but the DUP is the only party strong enough to unite around.
“Every first preference vote for another unionist candidate or another unionist party runs the risk of dividing unionism, returning fewer unionist councillors, and bolstering Sinn Fein demands for a divisive border poll.
“We are living in profound political times and there can be no doubting in these times that every vote matters.”
Deputy leader Nigel Dodds said a vote for his party is a vote to get the Northern Ireland Assembly back.
The institutions at Stormont collapsed in January 2017 following a breakdown in relations between the DUP and Sinn Fein.
“So much more could have been achieved with a working Assembly,” he said.
“The DUP has never seen influence in London and power in Belfast as a choice. The fact is the most will be delivered for Northern Ireland when they work together.
“It is unacceptable for Sinn Fein to hold the institutions and decisions on health, education and jobs to ransom for political demands.
“A vote for the DUP is a vote for the Assembly back now.”
According to the Belfast Agreement, Northern Ireland Secretary Karen Bradley has the authority to call a border poll “if at any time it appears likely … that a majority of those voting would express a wish that Northern Ireland should cease to be part of the United Kingdom and form part of a united Ireland”.
The DUP has consistently been the party with the biggest vote in Northern Ireland, while Sinn Fein has the second biggest.
At the 2017 Westminster election, the DUP won 292,316 votes, while Sinn Fein took 238,915.