BERLIN, Nov 4 (Reuters) - Germany"s Greens urged activist groups to lobby their would-be government coalition partners to accept stronger climate protection measures, after supporters of the party expressed dismay that a draft deal did not go far enough. In the undated letter, seen by Reuters, the party"s leaders admitted they had failed to win enough commitments from their Social Democrat (SPD) and liberal (FDP) partners and asked the activist groups, including WWF Germany, to help put their case. The leaders noted in particular a need to strengthen legislation to ensure that missed emissions targets automatically triggered measures designed to ensure that future goals were met. Until now, there have been few leaks from formal three-way talks, which began on Oct. 27, with the parties all publicly committed to forming an SPD-led government led by Olaf Scholz, the current finance minister. But the letter is a clear sign of difficulties they are facing in reconciling sometimes wildly different principles in the interests of agreeing a government programme. "It would be very helpful, and you are already doing this to some extent, if you could push for the SPD and FDP to take an ambitious approach," read the letter, signed by leaders including former Chancellor Candidate Annalena Baerbock. "If we have to keep doing this alone, negotiations will be much more difficult." While the Greens and SPD are close in areas of economic and social policy, the business-friendly FDP are more wary of measures that might make life harder for Germany"s crucial manufacturing industries. Few expect talks to fail, however, a point underlined this week at the G20 and COP26 climate summits by outgoing Chancellor Angela Merkel, who caused a stir by taking Scholz to meetings with other world leaders in what was interpreted as presenting her successor to the world. But the parties are still being cautious in what they communicate, mindful of the acrimonious collapse four years ago of negotiations aimed at forming a three-party government led by Merkel"s conservatives.