أن متمنِّعي صدام وحزب البعث
أن المتمنعنين الصداميين والبعثيين

A holdout is defined as "one that withholds agreement or consent upon which progress is contingent." This noun is derived from the verb "to hold out," which means "to continue to resist." The tiny snippet that you posted does not give us any clue as to what they are resisting or rejecting. You need to post sufficient context. Always.

One is tempted to call "holdouts" الرفضة or الروافض, except that both terms are commonly used as terms of abuse reserved for the Shi`a, so these terms may be confusing. The concept, however, is the same: The Shi`a are thought of as "holding out" as they continue to withhold consent to the line of succession after the death of the Prophet, upon which the Muslim masses have agreed.

شكرا

إن المتشبثين من مؤيدي صدام وحزب البعث...الخ

إن المتشبثين بصدام وحزب البعث.....الخ

'hold out' to continue to resist or stand firm as..a person refusing to succumb to persuation.

to hold out is to refuse to succumb to persuasion. Literally holding out to ideas and beliefs and refusing to compromise