French President Nicolas Sarkozy says he has received reassurances from Poland that the country will not block the ratification of the Lisbon Treaty.
Poland's President Lech Kaczynski had said it would be "pointless" to sign the EU reform treaty.
The agreement, defeated in an Irish referendum last month, must be ratified by all 27 states to come into force.
The two leaders discussed the treaty during a telephone call on Friday, the president's office said.
"The President of the Republic had a discussion with the President of Poland, Lech Kaczynski," the statement from the Elysee Palace said.
Mr Sarkozy, it added, "reminded him that the treaty was negotiated by President Kaczynski himself and Poland had pledged to ratify it".
The statement said the Polish president confirmed that Poland would not be an obstacle to the treaty's ratification. There was no immediate comment from the Polish presidency on the decision.
On Wednesday, Mr Kaczynski - a conservative who has long opposed the reform treaty - had said it would not be worth Poland signing it, even though Poland's parliament has ratified it.
- I'M DISGUSTED BY THIS SUPPOSED FLIP-FLOP.
- BUT IT SHOULDN'T MATTER: THE IRISH REJECTION SHOULD HAVE KILLED IT.
- IT'S OUTRAGEOUS THAT THE NATIONS WHICH RATIFIED IT ARE CARRYING ON AS IF IT'S ALIVE.
- THE EU CHARTER REQUIRES UNANIMITY.
- BY BARRELING AHEAD WITH THE TREATY ANYHOW, THEY ONLY FURTHER PROVE THEIR DISTASTE FOR DEMOCRACY - AND PENCHANT FOR TYRANNY.