Poland's president will sign the European Union reform treaty Saturday, completing the country's ratification process and leave the Czech Republic as the only EU nation yet to formally approve the document.

President Lech Kaczynski's office said in a statement Thursday that he will sign the Lisbon Treaty in a ceremony attended by European Commission President Jose Manuel Barroso.

Ireland approved the treaty Saturday, in a repeat vote, and now only Kaczynski and Czech President Vaclav Klaus need to sign the document for it to come into force. The treaty seeks to increase the 27-nation union's influence by making more decisions through majority voting rather than through the unanimous consent of all member countries.

If it is signed by Klaus, the treaty will take effect Jan. 1. Klaus says he is waiting for a ruling from the nation's Constitutional Court on a challenge from 17 senators questioning aspects of the charter.

On Wednesday, Czech Prime Minister Jan Fischer assured his EU partners that Prague will not derail the treaty, saying he was "fully and deeply convinced there is no reason for anxiety in Europe."

He said the Czech Republic's high court backed the treaty last year and predicted it would do so again, enabling Klaus to give his assent.

"Everything is in place for the ratification of the Lisbon Treaty ... by the end of the year," said Fischer.

