Stormont will "never be the same again" if TUV wins more seats at the next Assembly election, Jim Allister has said.
The party leader hailed a "rising tide" of support for TUV in recent opinion polls and declared that "TUV is here to win".
He railed against Brexit's Northern Ireland Protocol, calling for its "repudiation".
Read more: Crossgar Protocol rally: Unionists urged 'wake up' & maximise vote at upcoming Assembly election
And he challenged other unionist leaders to refuse to nominate a Deputy First Minister if Sinn Féin becomes the largest party in May.
Mr Allister has been TUV's only MLA in its 14-year history, but some recent polls suggest increased support for the party.
Speaking at the TUV conference in Cookstown, Co Tyrone, Mr Allister hit out at "naysayers" who write off the party's chances.
He said: "I've got news for our detractors: TUV is not in this election to make up the numbers. TUV is here to win.
"And when we do, I can promise you one thing: Stormont will never be the same again."
Mr Allister said TUV winning more seats would "advance the cause of traditional unionism" and "keep some others honest - or as honest as they can be".
He added: "Isn't it remarkable how the rising polls for TUV induced others to harden their stand on the iniquitous Protocol. They even want now to sing off our hymn sheet."
The North Antrim MLA heavily criticised as "constitutionally appalling" and "Union-dismantling" the Irish Sea trade border arrangements agreed by the UK and European Union.
He said: "There is no unionist surely, and certainly not in this party, who ever can or will come to terms with that obscenity of being treated as a foreign part within our United Kingdom.
"And all that will only get worse as the United Kingdom, the rest of it, diverges from EU rules."
Mr Allister hit out at DUP Agriculture Minister Edwin Poots for overseeing Protocol-related checks at the ports, branding them "Poots posts".
Referencing Mr Poots' recent move from the Lagan Valley constituency, the TUV leader added: "I see Mr Poots is now in an outpost called South Belfast."
Mr Allister also slammed UUP leader Doug Beattie's proposal of creating a cross-border body to manage Protocol issues.
He said: "This Protocol is irredeemable. It must go. No ifs, no buts."
Mr Allister criticised the Stormont government system of mandatory power-sharing between unionists and nationalists, calling instead for a "coalition of the willing".
Addressing his party conference at the Royal Hotel, he added: "TUV is very clear. If this Stormont can't be fixed, then it's not worth having."
Mr Allister said his party would never accept the Deputy First Minister role to "enthrone" a Sinn Féin First Minister.
"I can tell you, this party will never be bridesmaid for Sinn Féin," he said.
"My challenge today for other unionist leaders: Will they assure the unionist people of the same?
"It's a question that can't be dodged. It's a question they need to face. And when they dodge it, you can infer what the real answer is."
Closing his speech, he said: "Fellow delegates, we're in the great position that there is a rising tide of support for this party across this province.
"I have a simple message for you: Go back to your constituencies and work for victory."
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