FUNCINPEC and the Sam Rainsy party officials who ask to remain anonymous said the internal conflict of the Cambodian People's Party (CPP) is more serious than previous one.
The same officials believe CPP will announce leadership change in the near future.
The assumption was made after CPP president Chea Sim left for Thailand last week after he reportedly refused to sign the "block vote" bill into law.
It is also based on a recent report that said Mr. Chea Sim wished Mr. Rainsy luck during a phone conversation between the two leaders.
CPP vice president Hun Sen denied there was any conflict within his party.
CPP spokesman Khieu Kanharith said this is not the first time such rumor has surfaced.