People living south of the Border will be told "you may not have a vote but you do have a voice" in the 2014 referendum.
Willie Rennie, leader of the Scottish Liberal Democrats, will make the call at the party's annual conference in Brighton.
The LibDems are keen to see ordinary people as well as high-profile names, such as actors and footballers, speak up in favour of the union. But the move will be seen as a direct challenge to Alex Salmond, who has mounted a sustained campaign to win over English public opinion.
The party is concerned the only voices in the debate at the moment are anti-Scottish. Instead they want positive voices arguing the case for Scotland to remain part of the UK.
Mr Rennie told The Herald: "English nationalists tend to dominate the debate, saying Scotland should go and has nothing to contribute to the UK. I want to bring England and the rest of the UK into the debate to say what they value about Scotland and what they value about the UK so Scots know there is a moderate voice which values both."
Mr Rennie will tell delegates: "Despite what you may have heard, most people in Scotland don't want to leave. We want to stay – but it's not guaranteed. So I want to hear your voices in the debate about the UK's future.
"I want you to show the rest of the UK values Scotland and our partnership together."
He will urge the English, Welsh and Northern Irish to speak up for what the UK and Scotland mean to them.
Mr Rennie said that he wanted "a variety of voices" to be heard, including people from all walks of life – from ordinary citizens to those in power and with high profiles – and those with strong connections to Scotland as well as those with none.
"The danger is these moderate voices remain silent and let English nationalism dominate the debate. I want the moderate voice of England that it values Scotland and the UK to be heard loud and clear," he added.
"The independence referendum is a decision for Scotland to make on its own, but the people of England will want to express their support for the United Kingdom."
Earlier this year an ICM poll said more people backed Scottish independence in England than Scotland. However, there was not a majority in favour on either side of the Border.
Mr Rennie will also use the conference to urge the Scottish and UK Governments to learn from each other. The Coalition should follow Scotland's lead on equal marriage and minimum alcohol pricing, he will say, before calling on Scottish ministers to extend childcare to 40% of two-year-olds.
Scottish Secretary Michael Moore will tell the conference that Scotland benefits from a fairness "dividend" being delivered by his party. He will point to policies including the cuts to income tax for low and middle income earners, which the party says will save more than two million Scots a total of £1.2 billion in tax by next April.
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