Under proposals drawn up by Unite's regional committee in Scotland, union delegates will stay away from the Brighton gathering if the suspensions of two figures embroiled in the Falkirk row remain in place. A Labour source last night described the move as "self-indulgent" and also "damaging" to leader Ed Miliband.
Labour and Unite are at loggerheads over the way the union tried to secure the Falkirk candidacy for the latter's favoured candidate, Karie Murphy. Unite recruited more than 100 members in the town, but allegations emerged that some of the new members had not consented to joining the party.
Labour launched an investigation into the claims and put the local party into "special measures", while Murphy and Stevie Deans, who was both Unite's chairman in Scotland and chairman of the party in Falkirk West, were suspended.
The row prompted Miliband to condemn Unite and back far-reaching changes to the party's historic link with the unions.
Unite in Scotland has now written a draft motion offering its "full support" to Murphy and Deans. The motion also called on the union at a UK level to produce a resolution for local Labour parties to be "properly informed of the role of the union in the Falkirk selection".
It added: "This committee also calls upon the NEC [national executive council] to consider the most appropriate means of advancing the case of Unite and its activists in relation to the Falkirk selection issue at the 2013 Labour Party conference in Brighton."
On this theme, Unite in Scotland suggested a boycott: "Should the suspension of Stephen Deans regional chair and Karie Murphy regional political committee delegate still be in place, the position of the Scottish delegation to the conference will be one of non-attendance in support of Stephen and Karie."
The draft motion is expected to be handed to Unite's NEC imminently.
A boycott would inevitably take attention away from Miliband, who has struggled recently to set the agenda and mount effective attacks on the Conservatives.
One senior Labour source was scathing of the Unite motion: "This is damaging and self-indulgent stuff from Unite. Regardless of whether they believe they are in the right, a boycott will only harm the people who are desperate for a Labour government. It will only harm Ed's attempt at getting his message across to the country."
The motion is another example of the lengths to which Unite is going to help the suspended individuals.
The Sunday Herald revealed in July how Unite threatened to close the Grangemouth oil refinery down unless the company's owners lifted its own suspension of Deans, who works at the plant.
A Unite spokesman said: "It is a draft motion that is going to be sent to the executive council."
An SNP spokesperson said: "The depth of the rift that has opened up between Labour and Unite is laid bare in this scathing motion.
"Just when Ed Miliband believes he is managing to sweep the whole selection crisis under the carpet, his complete failure to address Unite's concerns looks set to come back to haunt him."
Labour declined to comment.