London ? Stung by an election defeat, Tony Blair shuffled his Cabinet on Friday and replaced Foreign Secretary Jack Straw in an attempt to save his own political future and shore up support to tackle crises in Iran and Iraq.

Straw had privately expressed doubts about the Iraq war to his boss and publicly took a different stance on Iran. He described military action against Tehran as “inconceivable,” something neither Blair nor President Bush would say, and called reports that the Bush administration has contingency plans for a tactical nuclear strike “nuts.”

Margaret Beckett, a Blair loyalist who has been serving as environment secretary, takes over the Foreign Office, becoming Britain’s first female foreign secretary. Blair’s spokesman said the change did not mean a shift in foreign policy.

Two ministers at the center of recent government problems also were fired or demoted.