By Sabine Siebold and Noah Barkin BERLIN (Reuters) - German parties negotiating a coalition deal have recommended holding nationwide referendums for major decisions on Europe in what would be a dramatic shift in policy, but Chancellor Angela Merkel looks likely to quash the proposal. The idea was spelled out in a document put together by one of the working groups discussing policy compromises to enable a government between Merkel's conservatives and the center-left Social Democrats (SPD). It calls for referendums when new members join the European Union, when powers are transferred from Berlin to Brussels and when Germany commits money at EU level -- a shift that could severely limit Berlin's ability to act swiftly in a crisis. But the proposal has yet to be approved by a larger coalition panel led by Merkel, and senior members of her Christian Democrats (CDU) made clear on Tuesday that they opposed the idea.