A member of Tonga's Friendly Islands Democratic Party says it may have the support of as many as 18 of the 26 MPs in the new parliament.
Negotiations over which of two camps will win the government benches is continuing with the election of the prime minister expected on Monday.
The nobles have claimed the support of a majority, but long time pro-democracy MP, Isireli Pulu, says that's not the case.
He says the Democrats have the backing of 14 of the 17 popularly elected MPs as well as a number of the nobles.
Mr Pulu says it's unlikely the nobles can remain a solid group.