Magazine Focus quoted representatives from both the conservative Christian Democrats and their federal coalition partner, the pro-business Free Democrats, who are unhappy with the chancellor's plans to see Germany abandon nuclear energy earlier than originally planned.
"The rapid nuclear-phase-out is one of the most disastrous mistakes made in German politics since 1949," Arnold Vaatz, deputy head of the Christian Democratic Union parliamentary party, told the publication.
In a worst-case scenario, the government's decision to turn its back on nuclear power could lead to "lasting power shortfalls and costly, bad investments."
The disaster at Japan's Fukushima plant, which experienced meltdowns at three reactors following the March earthquake and tsunami in the country, prompted German politicians to reevaluate their own nuclear policy.
The leaders of Germany's governing coalition recently endorsed plans for a gradual phase-out of nuclear plants over the next decade. The country's seven oldest nuclear plants, as well as the Krümmel reactor, will remain offline, while other facilities will be powered down in 2015, 2017 and 2019.
German Environment Minister Norbert Röttgen said three others would be turned off in 2021, with the newest plant to follow one year later.
Criticism for the plans also came from the FDP's federal deputy chairman, Holger Zastrow, who likened the phase-out to "an instance of planned economy."
In a guest commentary for German daily Frankfurter Allgemeine Zeitung, the CDU's floor leader in the Hessian state parliament, Christean Wagner, wrote that CDU supporters have lost basic trust in the party, describing the situation facing the CDU as "even more alarming than (it was) after the poor parliamentary election results."
Der Spiegel reported that Wagner has written an 11-page paper bemoaning the party's problems. The paper is now circulating among members of the CDU.