MANCHESTER, England — Prime Minister Tony Blair, in his final address to his governing Labour Party, said Tuesday that being the United States' strongest ally can be difficult but it is crucial to stay close to Washington in the fight against terrorism.

This speech was a chance for the prime minister to secure his legacy, to remind his detractors of his accomplishments and to urge his party to stay on course when he leaves office sometime in the next year.

Blair, 53, reminded the conference hall that when he first led Labour to victory, domestic issues dominated the agenda. Now, the challenges are global, he said, and include climate change, organized crime and religious extremism.

Because Labour won a majority in elections last year, if his possible successor, treasury chief Gordon Brown, is chosen as party leader he will become prime minister without having to face voters until elections expected in 2009 against the currently resurgent Conservatives.