BERLIN - German Chancellor Angela Merkel faces 'massive' public protests this fall as demonstrators attempt to derail her plan to prolong the use of nuclear power, the co-leader of the Green Party says. A movement that includes clean-energy businesses, doctors and students is preparing to confront Merkel over the planned extension of the running time of nuclear plants by an average of 12 years, Claudia Roth, co-chairwoman of the Greens, said in an interview Thursday. While the movement has echoes of the 1970s and 1980s rallies that gave rise to the Green Party, Merkel has awakened a 'new dimension' of opposition, Roth said. 'I can guarantee that this government has never experienced protests along the lines of what's coming,' Roth said in a phone interview from a party convention in the western city of Mainz. 'They won't be able to ignore it.' Germany's opposition groups are stepping up their campaign against nuclear power as Merkel seeks to steer the bill granting the extension through parliament. Her Cabinet is set to ratify the energy plan on Sept. 28. While she can rely on her majority to push the plan through the lower house, legal opinion is divided on whether Merkel can bypass the upper chamber, the Bundesrat, where her bloc is outnumbered by the opposition. Opposition Social Democrats have threatened legal challenges if she attempts to circumvent the Bundesrat. Merkel's popularity has sagged since her re-election a year ago. The ruling coalition dropped one percentage point to 36 percent support in a Forsa poll Wednesday, more than 12 points below its result in last year's vote. The Greens gained two points to 21 percent, the party's highest poll rating ever. It was the Greens, then led by Joschka Fischer, who helped author the phase-out of nuclear energy by about 2022 in a coalition with Chancellor Gerhard Schroeder's Social Democrats in 2002. 'The government is suffering not only on the nuclear issue, but also in other political areas,' said Hans-Juergen Hoffmann, head of Berlin-based pollster Psephos. With Merkel set overhaul health-care and cut spending on defense while facing further repercussions from Europe's debt crisis, the risk to her government 'is already recognizable in the political atmosphere and what you see in the polls.' A Sept. 18 demonstration, organized by anti-nuclear groups including Campact.de, will feature a march by tens of thousands of protesters to the Reichstag and a symbolic 'encircling' of the government quarter in Berlin, Campact director Christoph Bautz said by phone. Further 'huge protests' are planned in Gorleben, a nuclear-waste dump, and Stuttgart, Roth said. In Merkel's nuclear plan, she squelched the bickering between her Christian Democratic-led bloc and Free Democratic Party coalition partners to forge agreement on an extension of the licenses held by Germany's 17 atomic plants. The accord was excoriated by the opposition and activists as a giveaway to industry and harmful to the environment. Merkel spent this week defending the deal negotiated with the four main energy producers. More than half of the profit from extending plant running times will be put into renewable- energy development and the budget, Merkel said Monday. The government's plan is a betrayal of Germany's 'consensus' to exit nuclear energy, said Roth. That has bolstered the current protests beyond the traditional activist base to reach different age groups, church bodies and small businesses specialized in renewable-energy technologies who see their livelihoods at risk. 'The protests are much broader now -- they include a lot of young people who now know that nuclear power doesn't create jobs, but eliminates jobs,' Roth said. 'It's not just the old fighters who are out there protesting, but a lot of young people as well. Old and new movements have come together.' 