The US military is alleging that Jordanian-born Abu Musab al-Zarqawi has been attracting growing numbers of supporters to his groups.
A high-ranking US military official claims al-Zarqawi can count on between 500 to 1,000 armed men among his immediate support.
However, the unnamed US official stressed that al-Zarqawi's followers and other Iraqi resistance fighters with alleged Baathist leanings have probably never mixed.
"There have been some number of defections of Ansar al-Islam
individuals... The whole organization is far less capable than it
used to be. There are some numbers that have moved over and joined Zarqawi," the officer said.
But al-Zarqawi is quickly becoming persona non grata according to other Iraqi resistance groups. In statements made to Aljazeera last week, several Iraqi groups promised to hunt down al-Zarqawi and kill him if he did not halt his attacks on Iraqi civilians and interests.
In reviewing the multiple strains of anti-US violence in Iraq,
the officer was adamant that Zarqawi most likely never had any ties to the former president of Iraq, either before the US-led invasion in March 2003 or after.
"Saddam didn't have any love for foreigners and... thought they had to be very closely watched. We have not found any evidence he cooperated with Zarqawi himself... In any case, I think he would be very wary of that kind of cooperation with Zarqawi."
White House officials have repeatedly cited Zarqawi as a missing link between Saddam Hussein and the al-Qaeda network in the buildup to the 2003 war.
But despite the allegations, little is known about the man himself - and some experts even doubt he is alive.
Al-Zarqawi is believed to have fled from Afghanistan to Iraq in 2001 after losing a leg in a US missile strike on his Afghan base.
US officials argue it was at al-Qaida's behest that he moved to Iraq and established links with Ansar al-Islam - a group of Kurdish Islamists.
There is even speculation that al-Zarqawi was killed during a US attack on an Ansar al-Islam base last year.
Others, meanwhile, have accused the Americans of exaggerating the threat he poses to discredit resistance to their occupation of Iraq.