Barack Obama on Sunday said that Reverend Jeremiah Wright, his former pastor, was a “legitimate [campaign] issue”, surprising those calling on the Republican party to withdraw an advertisement that shows Mr Wright’s face morphing into that of Mr Obama.

The Republican advertisement shows a clip of Mr Wright saying “God Damn America” and then switches to a clip of Mr Obama and a burning American flag. In an appearance that could prolong the controversy, Mr Wright will on Monday address the National Press Club in Washington.