Washington: US President Barack Obama`s National Security Adviser Tom Donilon has declared one-time Egyptian doctor Ayman al-Zawahiri as the world`s "number one terrorist" after the death of Osama bin Laden.
"Our assessment is that he (Zawahiri) is not anywhere near the leader that Osama bin Laden was," The Telegraph quoted Donilon, as saying.
Intelligence officials and analysts believe Zawahiri’s abrasive style of functioning will make him unpopular with non-Egyptian ranks within the movement.
Other possible contenders in a succession battle include Abu Yahya al-Libi and Atiyah abd al-Rahman, two Libyans seen as rising stars.
Anwar al-Awlaki, the American-born radical cleric famous for his YouTube appeals to English-speaking converts from his base in Yemen, has also been mooted.
However, his high-profile in the West is not matched by his status within the terror network. He has little combat experience, no links to bin Laden and is a member of Al-Qaeda in the Arabian Peninsula – an offshoot of the core leadership.
American officials have described the succession as an "open question".
"Zawahiri is obviously the presumed successor, but there are strong indications that he is not popular within certain circles of the group," said a senior CIA official during a briefing to reporters at the weekend.