June 14 (Bloomberg) -- Securing agreement on a European Union treaty will be a ``Herculean task,'' German Chancellor Angela Merkel said, amid a flurry of diplomatic effort to strike a deal before a summit of EU leaders.

Merkel, as holder of the EU presidency until the end of June, is trying to rally the 27-nation EU behind the broad outlines of a new treaty to replace the constitution that was torpedoed by French and Dutch voters in 2005.

``We have a chance to approve the road map'' on how to move forward with the treaty at the EU meeting in Brussels June 21- 22, though ``road map is too simple a word for such a Herculean task,'' Merkel told lawmakers in Berlin today. ``We have a chance -- no more, no less.''

Poland has threatened to veto the planned overhaul of EU decision-making machinery, escalating the brinksmanship over how to salvage the bloc's failed constitution. Polish President Lech Kaczynski said after talks with his French counterpart Nicolas Sarkozy in Warsaw today that he may be prepared to give ground.

``We are ready for a compromise, but not for a system that sharply lowers the ranking of Poland in the EU,'' Kaczynski told reporters, adding: ``We don't want to be isolated.'' He and Sarkozy ``are both convinced that June 22 should be a day of success,'' he said.

Berlin Talks

Kaczynski made his comments two days before he is scheduled to meet Merkel outside Berlin for pre-summit negotiations. Merkel also plans to hold talks with Dutch Prime Minister Jan Peter Balkenende in Berlin tomorrow.

EU leaders aim to end negotiations on the treaty by December so that all 27 countries can ratify the new treaty in time for the mid-2009 European Parliament elections.

Poland's Prime Minister Jaroslaw Kaczynski has said he is prepared to block any revamp of the voting system -- designed to tilt EU powers from small to large countries -- that would strengthen the hand of large countries such as Germany.

``A solution is still not in sight,'' Merkel said today. ``It can only be found unanimously and in a way that brings Europe forward.''

Poland should ``participate in a compromise and stay away from isolation,'' Sarkozy said at the joint press conference with Lech Kaczynski in Warsaw. ``Not everything is solved,'' he said, adding that ``all topics will naturally be on the table.''

`Square Root or Death'

Poland favors assigning votes on EU laws under a new formula based on the square root of each country's population, and has adopted the rallying cry: ``Square Root or Death!''

Germany has a population of 82.4 million, producing a square root of 9,077. Poland's population is less than half the size of Germany's at 38.5 million, yet the square root at 6,205 would give it a voting weight two-thirds that of Germany.

The Polish President reaffirmed his government's commitment today to the ``just'' square-root system, adding that he wanted a solution that ``satisfies Poland and other countries.''

The constitution uses the overall population, handing more power to Germany than to Poland. Laws would pass when backed by a ``double majority'' of at least 55 percent of the national governments representing at least 65 percent of the EU's population. Merkel wants to stick with that formula.

``We are full of good will towards our German partners,'' Kaczynski said, adding that he ``understands'' Germany's position on wanting voting according to population. ``It is all about proportions and the square-root system reflects proportions very well.''

EU President?

All EU leaders signed off on the constitution in 2004. The treaty, which would streamline decision-making and create the posts of president and foreign minister, requires unanimous ratification and so far 18 of the 27 member states have done so.

``Almost all countries are working on a solution'' with ``only one or two cases where one can't be sure whether there will be a realistic exchange of arguments and compromises,'' Elmar Brok, a German Christian Democrat member of the European Parliament, said in an interview. ``There is an 80 percent chance that we will succeed next week.''

Sarkozy said it was important that EU leaders meeting in Brussels ``take Polish sensibilities into account.''

``It will be a long night,'' he said.

To contact the reporter on this story: Claudia Rach in Berlin at crach1@bloomberg.net.

Last Updated: June 14, 2007 09:07 EDT