Scottish Labour, Conservative and Liberal Democrat leaders are being asked to say whether they will allow all their members to choose sides freely in Scotland's independence debate.
The move from Green MSP Patrick Harvie came ahead of the 9 February 2012 party leaders’ meeting on the referendum.
The unionist parties are being requested to give MSPs, MPs and councillors the chance to campaign openly on any side of the debate.
The Greens back the referendum, but argue that the independence debate should not be constructed along party lines, and that the debate in the run up to the 2014 poll will not benefit if dissenting voices are shut down by party managers.
Green MSP and party co-convenor Patrick Harvie explained: “Over the years I’ve met members of all parties who are more open to independence than their parties will admit, and it’s not hard to find some who are privately enthusiastic."
"It’s important for our democracy that they should feel free to speak their minds, and to campaign for a Yes vote without fear of party discipline," he continued.
“Independence has too often been seen as a simple split down party lines, but the truth is more complex than that.
“Party leaders can sit down today and discuss the timing, the question, votes at 16, and a host of other issues. But the referendum is too important to be carved up between five people behind a closed door.
"Everyone in Scotland, including those in parties that don’t support independence, must be free to campaign for the result they really believe in,” concluded Mr Harvie.