France and Germany are urging other European Union members to reach agreement this weekend on a draft constitution for the bloc and are raising pressure on Poland and Spain to back away from their opposition to new EU voting rules enshrined in the document.

It was billed as an informal lunch, but Tuesday's one-hour meeting in Paris between French President Jacques Chirac and German Chancellor Gerhard Schroeder was, more than anything else, a sign that Europe's two powerhouses have closed ranks behind the existing constitutional draft.

France and Germany say the draft, as it stands, or with only a few minor modifications, is essential for the EU to function when 10 new members join next year.

But Poland and Spain are threatening to block agreement on the document, which must be approved unanimously by all current and future members.

Poland and Spain are fiercely resisting proposed changes in the EU's voting system and insist on keeping the current rules, which allow them an influence in decision-making that is disproportionate to their population.

Standing next to Mr. Schroeder outside the Elysee Palace, President Chirac Tuesday said he could not imagine that one or two countries could "block the progress that others want to make."

He said that he and the chancellor will not accept an accord at any price but want an agreement that reflects their idea of what Europe should look like in the future.

French diplomats say the message coming out of the Franco-German meeting is that, if Poland and Spain do not yield, they will be blamed for the failure of the summit.

But diplomats from smaller EU countries say France and Germany, which have long been the engine driving European integration, have lost influence among their partners in recent weeks by flouting EU budget rules. That has made some small countries wary of any move that would give France and Germany more power.

Nearly all of the smaller countries want to be represented on the EU's executive commission, but France and Germany say a commission with 25 members would be unwieldy.

French and German officials have in the past said that, if the constitutional negotiations fail, their countries and other like-minded nations will simply press ahead with closer integration and create a two-speed Europe, leaving those unwilling to join them behind.

But Mr. Schroeder says the priority now is to get a deal in Brussels, not just any deal but one that Germany and France can live with. Though the summit is scheduled to end on Saturday, the negotiations are expected to continue into Sunday and even Monday. One Spanish diplomat says he is packing five shirts, just in case.