French centre-right candidate Nicolas Sarkozy has set out his foreign policy vision ahead of presidential elections in two months' time.
Nicolas Sarkozy has been slipping in opinion polls
He said he would make France a closer partner with the US, but would not confuse friendship with "submission".
Mr Sarkozy repeated his opposition to the US-led war in Iraq. He also promised a robust foreign policy with a strong emphasis on defence.
He is running neck and neck in polls with Socialist hopeful Segolene Royal.
Mr Sarkozy - who is also interior minister - is widely seen as better disposed towards the US than incumbent Jacques Chirac.
In a foreign policy speech on Wednesday he said: "I want a free France, I want a free Europe. I therefore ask our American friends to leave us free, free to be their friends."
Friendship, he said, was not "submission".
Mr Sarkozy added that close ties with Washington were "a necessity for the balance of the world".
The BBC's Emma Jane Kirby in Paris says Mr Sarkozy's position is a very different stance to that of Mr Chirac, who feared America's weight tipped the world off balance.
Mr Sarkozy also said Europeans should rely more on themselves for their defence, and pledged to maintain the nuclear deterrent - which he called an "absolute imperative" and "the life insurance of the French nation".
On Europe, the centre-right candidate said he would resolve the crisis triggered by the rejection of a draft EU constitution by French and Dutch voters in 1995.
He said he would propose a "simplified treaty" to insure that European institutions "start working again".
Mr Sarkozy's lead over Ms Royal has been greatly reduced in recent days.
Polls suggest both enjoy about 30% support - although Mr Sarkozy remains slightly ahead.
They face a challenge from centrist candidate Francois Bayrou, who has climbed to 17%, outscoring far-right leader Jean-Marie Le Pen.