World Bulletin / News Desk

Germany's second biggest party will announce Sunday the result of their members' high-stakes vote on whether to join Chancellor Angela Merkel's coalition, a decision that will determine her future after five months of political stalemate.

But with the SPD bitterly divided internally over its way forward following abysmal election results in September, it had also promised its more than 460,000 card holders the final say on the accord.

If the rank-and-file of the 153-year-old labour party gives the thumbs up, Merkel could launch her fourth government by mid-March.

If they torpedo the deal, Europe's biggest economy faces snap elections that could hasten an end to Merkel's leadership after 12 years in power.

The SPD's leadership is appealing to members' sense of responsibility to voters as it urges them to approve the coalition deal.

Party chiefs also argue that they have wrested a maximum amount of concessions from the conservatives, including control over the crucial finance and foreign ministries.

A survey published by YouGov in the final days of the voting, which began on February 20 and closed Friday, suggested that the yes camp is slightly ahead, with 56 percent of SPD supporters among the public backing a new partnership with Merkel.

It is not clear whether card-carrying SPD members are equally open to the deal.

Top SPD politicians including Foreign Minister Sigmar Gabriel have also voiced confidence that members will plump for a new round in government.

But the SPD's young members have spearheaded a rebellion, with the party's youth wing leader criss-crossing the country over the last weeks making an impassioned case against the coalition.

They argue that governing for another four years under Merkel's shadow would sound the death knell for the party.