Germany could allow its citizens to vote on the European Union constitution after all. If a two-thirds majority in the Bundestag -- the lower house of parliament -- voted to amend the country's constitution to allow for referendums, one could take place to decide on the EU document, government spokesman Hans Langguth said on Monday. But he ruled out a decision that would only allow an isolated referendum on the one issue. Both the opposition CDU and the FDP criticized proposing such legislation, calling the move populist and deceptive. Without the opposition's support, the bill would not garner the necessary majority in parliament. Social Democratic Party head Franz Müntefering announced on Sunday his party would vet the legislation to change the German constitution in the fall.