What has become known as the Lisbon Treaty easily passed the necessary two-thirds majority in Germany's upper house of parliament, the Bundesrat, on Friday. The treaty aims to make the 27-member bloc more efficient.
The Bundestag represents Germany's 16 states
The Bundesrat approved the new EU treaty on Friday, May 23.
The vote was its last legislative hurdle in the 27-nation bloc's most populous country.
The Bundesrat represents the country's 16 state governments. All but one voted in favor.
The Bundestag, the lower house of parliament, last month overwhelmingly backed the Treaty by 514 votes for to 58 against, with one abstention from Berlin.
By abstaining, Mayor Klaus Wowereit effectively voted 'no' but thereby averted a stand-off within the Berlin government between his own Social Democrat party and its coalition partner, the Left party.
The Left draws most of its support in the former communist east of the country, and sees the treaty as opposed to its social policies.
Wowereit was sharply critical of his coalition partner. Party leader Oskar Lafontaine had demonstrated that "the Left is not capable or ready to be in government at federal level," the mayor said ahead of the vote.
The 53 members of the Left made up the bulk of the opposition during the Bundestag's vote last month.
Some of them have signalled they might now mount a constitutional challenge to the treaty through the courts.
A "new foundation"
Klaus Wowereit staved off a crisis in his government
Chancellor Angela Merkel, who was one of the main drivers of the process leading up to the slimmed down treaty, described it as "good for Europe" and a "win for Germany" -- and said it creates "nothing less than a new foundation for Europe."
Only President Horst Koehler's signature is now required to complete ratification.
The treaty was signed in the Portuguese capital on Dec. 13. It replaces the failed European constitution, which was abandoned after the French and Dutch rejected it in referenda in 2005.
The 27 EU member states are being asked to ratify the treaty by the end of the year, ahead of elections to the European Parliament in 2009. Ireland is to hold a referendum on the treaty in June -- the only country to do so.
The treaty, a complex legal document comprising a string of amendments to previous EU deals, aims to streamline decision-making through increased use of majority votes and creates the offices of an EU president and foreign policy supremo with clout.