Colak was quoted by the Bosnian edition of the Vecernji List daily as saying on Tuesday that such speculations were unreal and ridiculous.
He added that he expected the forthcoming convention to elect a new party leadership.
The recent decision of international High Representative Paddy Ashdown to dismiss the Croat member of the country's three-man presidency, Dragan Covic, an HDZ official, triggered off speculations on how Covic's replacement could lead to changes within the HDZ BiH after Ashdown enabled Covic to continue with his political work in the party.
Some media also predict that a rift in the HDZ BiH could also cause a political crisis in Bosnia.
Colak said that his party would act fully in compliance with laws and the Constitution of Bosnia-Herzegovina.
The new Croat member of the Bosnian collective presidency is expected to be elected next week, when the Bosnian parliament's House of Representatives convenes again, MPs said after the lower house in Sarajevo met on Tuesday.
According to media reports, Martin Raguz and Ivo Miro Jovic of the HDZ stand the best chances to be elected as Covic's successor.