Following a White House denunciation of Carter's original remarks, the Democratic former leader said he had intended to describe Bush as the worst president since scandal-plagued Richard Nixon.

"My remarks were maybe careless or misinterpreted. But I wasn't comparing the overall administration and certainly not talking personally about any president," Carter told NBC.

"I have been very careful and still am not to criticize any president personally," he said, while restating his opposition to Bush's policies on Iraq and the Middle East.

In a weekend commentary published by the Arkansas Democrat-Gazette, Carter had written: "I think as far as the adverse impact on the nation around the world, this administration has been the worst in history."