Ulster Unionist leader Doug Beattie has accused the DUP of deploying scare tactics as polling day approaches.
Mr Beattie was reacting to comments from Sir Jeffrey Donaldson, who had claimed next month’s Assembly election is a battle for Northern Ireland itself.
Mr Beattie claimed the DUP was “desperate” to raise the prospect of a border poll to win over voters.
At the weekend, Sir Jeffrey used an Easter message to party colleagues to warn that a Sinn Fein victory on May 5 would help it deliver on its objective for a referendum on Irish unity.
He claimed the election will “set the direction of the country for the next decade”.
Sir Jeffrey told colleagues: “Over the last week, I have been focusing on constituencies where unionism is only chasing one seat.
“I have been reminding the people in those areas that voting for parties that can’t win will risk the seat.
"Despite what some people say, you can split the vote too thinly in a PR election.
“I am also reminding them that this is a battle for Northern Ireland.
“The DUP is the only party that can stop Sinn Fein’s divisive border poll plans. A first preference vote for any party other than the DUP will divide and weaken the unionist cause and help Sinn Fein win and deliver on their border poll plan.”
But Mr Beattie urged people not to be “fooled” by the DUP’s warnings.
“The DUP are trying to scare unionists into voting for them by raising fears of a border poll and by saying only they can beat Sinn Fein,” he said.
“This is clearly wrong and the unionist electorate, indeed the whole electorate, should not be fooled by this tactic once again.
“To vote is important, to vote out of fear is unnecessary.
"People should focus on policies and vision and not allow unfounded fear drive them to the polling station to vote for a party desperate to raise the spectre of a border poll when there simply isn’t one.”
Sinn Fein has said that its focus in the election is on pressing health and economic issues in Northern Ireland, such as the cost-of-living crisis and spiralling hospital waiting lists.
But Sir Jeffrey has dismissed this and claimed that Sinn Fein’s focus after the election will still centre on what he called a divisive border poll.