Ljubic, Raguz and Merdzo have recently launched the signing of a memorandum that insisted on a new election convention to replace the current HDZ chief Dragan Covic.
The three former high-ranking party officials accuse Covic of pushing the party into isolation.
Covic was elected as party leader in early June. The convention was marked by controversies and the main rival for that post, Bozo Ljubic, then accused Covic of rigging the results of the election.
Also, the European People's Party, in which the HDZ BiH has observer status, has suggested that Covic should not be at the helm of the party as long as he is standing trial on corruption charges.