Mrs Merkel made the constitution a priority of Germany's EU presidency
German Chancellor Angela Merkel has said that agreement on a new EU constitutional treaty was "still not in sight" ahead of an important EU summit.
But Mrs Merkel told parliament in Berlin she hoped the summit would take a clear step forward and produce a "roadmap" to a new treaty by 2009.
French President Nicolas Sarkozy is due to visit Poland on Thursday to smooth the way ahead of next week's summit.
French and Dutch voters rejected a proposed constitution in 2005.
"We want to agree upon a roadmap next week," Mrs Merkel said in a speech to the Bundestag, the lower house of parliament.
The plan would lead to a new EU constitutional treaty by 2009.
"This is not just up to us, but we will do our part. If this doesn't succeed, it will not yet be the downfall of Europe, but it will have... extremely serious consequences."
The German chancellor added that a solution was essential to enable the enlarged EU bloc to "function properly".
Efforts to revive the project have highlighted sharp differences over how extensive the constitutional changes should be.
The BBC's Steve Rosenberg in Berlin says the main stumbling block is Poland, which is threatening to veto a deal on the future of the charter, refusing to accept changes to the voting system envisaged under the draft treaty.
Under the new double majority voting system, Poland is set to lose out the most.
Mrs Merkel has made the constitution a priority during Germany's presidency of the EU - which comes to an end at the end of June - and her reputation hinges on securing a deal, our correspondent says.