Within the Social Democrats (SPD, which is rather down in the polls), there is great unison between the Coal, Gas and Renewables party wings (</snark>) against nuclear. After Krümmel, it seems they think clubbing the CDU with the nuclear issue with a popular demand (72% want the immediate closure of the oldest plants) can be a suitable last-ditch effort.
In Germany it's still a very hot potato, while in Sweden it's a wedege issue for the right, which repeatedly bashes the left with it, as the leftist elite (and for a long time also the bourgeoise elite) are strong opponents, while the general population is the most pro-nuclear in the entire world!
If I speculate this might have something to do with us not having any coal/gas special interests, and renewables means either biomass heat or hydro, the latter which is dominated by big players with massive nuclear assets (Vattenfall, E.On and Fortum).
I also think it's related to our extremely exhaustive 40 year debate on nuclear. This huge exposure means the public has had to learn the basic technical issues and with that the fear of the "unknown" and spooky "radiation" has receded. Peak oil is not an energy crisis. It is a liquid fuel crisis.
I would say that also reflects the reason the question is looked at "keep current plants", in addition to the question in the 80ies breaking up the swedish bloc system and making majority governments impossible for a while. A vote for PES is a vote for EPP! A vote for EPP is a vote for PES! Support the coalition, vote EPP-PES in 2009!