Leaders of Hollywood’s two biggest performer unions are going off the radar later this week to focus on what may be the final proposal for merging the Screen Actors Guild and the American Federation of Television & Radio Artists,

Starting Saturday, they’ll hold a marathon nine-day meeting with the goal of prepping the proposal in time for the national boards at the end of the month. And in a move that underlines the importance for union toppers to generate an acceptable merger proposal, several sessions have been set for the Renaissance Hotel away from the SAG and AFTRA offices in Hollywood.

Spokespeople for the unions had no immediate response Monday. But a source familiar with the situation indicated that using the off-site location is aimed specifically at giving union reps the best chance at working through dozens of complications presented by combining the SAG and AFTRA — and meeting the previously announced deadline of wrapping up the process this month.

SAG currently has about 120,000 members while AFTRA has about 70,000, with about 45,000 performers belonging to both unions. Should the proposal be approved by the national boards, members could be asked to OK the merger in a referendum that would require 60% of those voting in each union to approve.

SAG members defeated merger proposals in 1999 and 2003 while AFTRA members supported both. Concerns over SAG’s loss of identity and the impact on the SAG-producers health and pension plans were raised in the 2003 vote, when a merger was supported by 58% of SAG members who voted.

The official AFTRA and SAG Group for One Union has held four meetings since June, most recently on Dec. 11-12 when the upcoming nine-day meet was set. The meetings have been facilitated by Rutgers School of Management and Labor Relations professor Susan J. Schurman and labor consultant Peter S. DiCicco.

The G1 includes half a dozen workgroups, which have been hammering out details such as a name, governance, financing, membership requirements and dues. Other than describing the meetings as productive, the unions have disclosed only general details about the substance of discussions.

SAG’s elected leadership has been dominated in recent years by pro-merger reps, who contend that a combined union would be more powerful and remove jurisdictional overlaps. Opponents, who have seen their influence wane, contend that the new union should be for actors only.