EU nationals who have made the UK their home should have the right to vote in the referendum on whether to sever ties with Brussels, Scottish Labour leadership candidate Kezia Dugdale will say on Saturday.
Dugdale will state that she strongly believes it would be "unfair" to exclude EU citizens from such a fundamental decision.
She is expected to claim that last September's referendum on Scottish independence was enhanced by the participation of around 90,000 EU nationals registered to take part in the ballot.
"Put simply, I believe EU nationals who have chosen to live their life here, and make the UK their home, should have the right to vote in a referendum on the future of the country," Dugdale will tell an audience in Glasgow.
The Lothians MSP - the Scottish party's deputy leader - will set out her position in a keynote speech to the Scottish Fabians later this afternoon, in which she will also argue that Scottish Labour has to be seen as a party with ideas for the future rather than stuck in the past.
The address comes days after it emerged that citizens from most European Union countries living in the UK will be barred from voting in the referendum on membership of the EU, promised by Prime Minister David Cameron.
The franchise for referendum, expected by the end of 2017, will be based on that for a general election - meaning Irish, Maltese and Cypriots resident in the UK will get a vote, but other EU citizens will not.
Dugdale will tell the audience she will be campaigning to stay in Europe and keep the "strong ties" with the UK's neighbours.
She will say that referendums should be conducted "as inclusively and democratically as possible" and will argue that 16 and 17-year-olds should be able to vote in the EU referendum, as they did in the Scottish independence ballot.
But she will tell the audience: "I would go further. When we had our referendum in September, just under 90,000 EU nationals registered to take part and it was the better for it.
"Put simply, I believe EU nationals who have chosen to live their life here, and make the UK their home, should have the right to vote in a referendum on the future of the country.
"EU nationals make important contributions to our communities, and to our economy.
"The influx of talent, creativity, and a different perspective of work and culture enriches our society as a whole, resulting in a more diverse and innovative society.
"We as a country benefit from the free movement of people across Europe, and we should not continue to enjoy this freedom while restricting political participation.
"Voting rights are a matter of democratic principle, and I strongly feel it is unfair to exclude EU nationals from a fundamental referendum.
"The referendum reinvigorated political participation in Scotland. A referendum on Europe can afford us the same opportunity.
"Rather than divide and exclude people, we should be coming together as a society to decide the best way forward."
Dugdale is expected to face a challenge from Labour MSP Ken Macintosh in the bid to replace outgoing Scottish Labour leader Jim Murphy.
Murphy is to step down from the post next month in the wake of the party's poor general election performance, in which it lost all but one of its MPs north of the border.
Reflecting on the "agonising" defeat, Dugdale will warn later against a return to "business as usual" for the party.
She will say: "In defeat, it is natural for us to turn to the highlights of our history to find solace, comfort.
"We'd turn our backs to the harsh winds of truth and huddle together for safety. Grieve together for what might have been and then more often than not, move on in broadly the same direction we've taken before.
"And sometimes that road has worked, a slight detour, a simple delay along a path to success. A minor adjustment on the course for better times ahead. Not this time.
"There is but an episode in a series of defeats that the Scottish Labour Party has now entered. We have been here too often in recent years. The answer cannot be keep calm and carry on campaigning.
"Politics in Scotland has now changed quite fundamentally and we have but one chance to get it. And get it we must."
She will caution against an "arrogant presumption that there must always be a Labour Party in Scotland" and insist: "What we see today as a disaster we can choose to redefine as a huge opportunity."
She will tell the gathering: "We have to accept that if we don't change our ways, there will be nothing left to protect."
Stephen Gethins MP, the SNP's Europe spokesman at Westminster, said: "It's absolutely vital the referendum on Europe is as inclusive as possible - following the example of Scotland's referendum last year - which is why the SNP has been leading the fight against this Tory Government's attempt to silence the voices of our EU nationals.
"I am pleased that Labour in Scotland now appear to be backing the SNP position on allowing our young people and EU nationals the right to vote. I now hope that Labour at Westminster will follow suit and join the SNP in opposing this unfair and discriminatory policy."