Lord Fusitu'a said there have been a series of breaches of the rule of law, of the principles of democracy and the Constitution under the government of 'Akilisi Pohiva.
Mr Pohiva had already survived a vote of no-confidence and another such vote cannot be submitted until next year but Lord Fusitu'a said a group of MPs are looking at other avenues to remove the prime minister.
He said something needs to be done because there was discontent and disillusionment throughout the country.
"It's definitely throughout the community and the country but it is even more acute in parliament because we have more of an inside knowledge of what this current administration is doing publicly and behind the scenes," he said.
"So, current breaches of the rule of law that the public are aware of and current breaches of the rule of law that the public are not aware of which I understand will be the grounds for a number of impeachment's."
Lord Fusitu'a said the prime minister can't be allowed to finish his term if the country was to prosper.
Even though there was little more than 18 months remaining in that term, Lord Fusitu'a said public sector sackings and the recent withdrawal for the support of the Pacific Games hosting illustrate that action was needed urgently.
"It's unconscionable for us to let the country suffer for another year and a half and they may not say so but I think our Pacific neighbours, both the metropolitan and the island nations, would agree that something needs to be done to get Tonga back on track," he said.
Lord Fusitu'a said there may also be an attempt to block the budget.
Photo: AFP 'Akilisi Pohiva