A vote of confidence in Somalia's prime minister, seen as a power-struggle between the leader of the government and President Sheikh Sharif Ahmed, has been postponed, Reuters quoted officials as saying on Saturday. Prime Minister Omar Abdirashid Sharmarke has come under intense pressure to step down in recent months, with Ahmed leading calls for him to go. Legislators voted on Thursday to hold a confidence vote on Saturday but there were not enough MPs present for a quorum and the parliament speaker said the session would not take place. Opponents of the prime minister said they now wanted a session on Sunday, but it was not clear whether it would happen. Under Somalia's constitution, Sharmarke's opponents require a simple majority to oust him. One legislator, however, said on Saturday the prime minister had sufficient support to survive. "We are 351 MPs in Mogadishu and 186 out of these are for the prime minister. Where can they get 276 MPs to vote against our prime minister?" legislator Mohamed Abdullahi Waqaa told Reuters. Officially there are 550 MPs in the Somali parliament although far fewer usually attend. Three hundred must be present for the session to be valid.