Winning Northern Ireland's assembly election would give Sinn Féin a "hugely significant worldwide propaganda boost", the DUP leader has said.
Arlene Foster said this would be a disaster for Northern Ireland, and stopping the party was the platform on which the DUP was seeking a mandate.
Mrs Foster listed 10 reasons the issue mattered if people asked about it on the doorsteps.
The former first minister was speaking at a low-key manifesto launch.
The eight-page DUP document was described as "an addendum to reflect developments since last May" - when the last assembly election was held.
It refers back to the party's five-point plan which, it said, remained as relevant now as nine months ago.
The five points were:
- Prioritising spending on the health service
- Creating more jobs and increasing incomes
- Protecting family budgets
- Raising standards in education for everyone
- Investing in infrastructure
Mrs Foster's speech contained 31 mentions of Sinn Féin, 12 of its president Gerry Adams and just one of its new northern leader, Michelle O'Neill.
The DUP leader made no reference to the Renewable Heat Incentive (RHI) debacle which was the reason Sinn Féin gave for quitting the Northern Ireland executive last month and forcing an election.
She explained at the start of the manifesto launch that she was suffering from "man flu" and afterwards, she took no questions from the media.
In her speech, Mrs Foster said all the recent polling suggested it would be "neck-and-neck" between her party and Sinn Féin.
She attacked Ulster Unionist leader Mike Nesbitt for saying he would be giving his second preference vote to the SDLP, calling the move "sad and shameful".
"I know other parties don't like us saying it, but the reality is that every vote for another unionist party is a vote which is lost in the battle to make sure that Sinn Féin does not win this election," she said.
Mrs Foster's 10 reasons for opposing such an outcome included claims that it would:
- Give Sinn Féin an excuse to use it as justification to call for a border poll
- Make devolution harder to restore
- Threaten economic recovery by undermining the prospects for a reduction in corporation tax
- Allow Sinn Féin to take the justice ministry; and it would lead to a "sectarian abuse of power"
She concluded: "It would give Gerry Adams and Sinn Féin a hugely significant worldwide propaganda boost just months after nationalism's worst election since 1993 and would undermine the unionist confidence which is being rebuilt after so many years in decline.
"And finally, it would, of course, give Sinn Féin the right to nominate a first minister - our job is to make sure that does not happen."
On the negotiations which will likely follow the election, Mrs Foster said her party did not want to construct any red lines or barriers to the restoration of the executive.
She said the DUP would honour all previous commitments, on the basis that republicans do the same.