Thirty-seven of the main opposition Malawi Congress Party (MCP)'s 41 political district chairmen have openly declared that they do not want party president Gwanda Chakuamba as their leader.
The 37 made their declaration at a public rally addressed by Mr Tembo in the capital, Lilongwe, late on Sunday afternoon. One by one the 37 went up to the dais and declared their allegiance to Mr Tembo.
This is just the latest stage in a very public fall-out between the two leaders since the MCP was edged out of government in 1994, after an uninterrupted 30 years in power.
The MCP district chairmen said they have lost confidence in Mr Chakuamba after, among other things, two consecutive general election defeats.
New start
Mr Tembo, who appeared happy with the resounding endorsement, told the sizeable crowd he was ready to re-build the divided party once he was given the mandate.
But Mr Chakuamba dismissed Mr Tembo's Lilongwe rally. He said this was the height of his deputy's rebellion against him.
"Mr Tembo is power hungry. He assembled a group of his loyalists, distributed some money among them and choreographed for them what he wanted them to say," he said.
Meeting ahead
Mr Chakuamba said he has written letters to all the MCP national executive committee members summoning them to a meeting in Lilongwe next Friday to thrash out the differences between him and his deputy.
But Mr Tembo and executive members loyal to him have openly rejected the invitation.
The problems created by this rift came to the fore last August when loyalists for both men called separate conventions, where each faction elected its own favourite as president of the same party.
The MCP had to go to court to solve the problem.
The court decided that Mr Chakuamba was the leader of the party, but Mr Tembo's supporters have never accepted that.