BERLIN, Nov 27 -- Talks on forming a new German "grand coalition" with the Social Democrats (SPD) may not begin until next year, a top official in Chancellor Angela Merkel's conservative camp said, potentially prolonging the uncertainty in Europe's largest economy.

Merkel, whose fourth term was thrown into doubt a week ago when three-way coalition talks with the pro-business Free Democrats (FDP) and Greens collapsed, was handed a political lifeline by the SPD on Friday.

Under intense pressure to preserve stability and avoid new elections, the SPD reversed its pledge to go into opposition and agreed to discuss supporting a Merkel government, raising the prospect of a continuation of the grand coalition, which has ruled for the past four years, or a minority government.

But Julia Kloeckner, vice-chair of Merkel's Christian Democrats (CDU), said talks may not begin until the new year, over three months after the national election in which the two biggest parties suffered punishing losses.

"Thoroughness comes before speed," she told ARD television. "I expect talks to begin in the new year," she said, adding a plea for the SPD not to set out red lines that might hinder talks before they start.

In Merkel's 12 years in power, her junior coalition partners have seen precious little reward from voters for joining government, and SPD rank and file are reluctant to repeat the experience.

SPD leader Martin Schulz has pledged to give members a vote on any deal the party reaches with Merkel. Many members advocate a looser arrangement whereby the SPD agrees to tolerate a Merkel-led minority government, supporting or at least agreeing not to vote against certain measures.

A poll for RTL and NTV television showed 48 percent of SPD members were in favour of toleration, an inherently less stable form of government, and only 36 percent in favour of a renewed grand coalition.

Following the collapse of talks with the FDP and the Greens, the SPD represents Merkel's last chance of securing a fourth term as chancellor. Most experts say this gives SPD more leverage despite their election losses.

In a sign the SPD intended to use that leverage, SPD vice-chair Ralf Stegner called on Merkel's camp to pave the way for talks with "confidence-building" measures, including worker-friendly employment legislation the SPD has long backed.