The Speaker of Tonga's Legislative Assembly, Lord Lasike, has had his position revoked and he has been barred from parliament.
This follows his conviction last week on a charge of illegal possession of ammunition.
While he was fined, the offence carries a maximum term of five years imprisonment and the Lord Chamberlain has ruled that that means he must forfeit his seat in Parliament.
On Tuesday, a planned vote of no confidence was adjourned while MPs sought clarification on Lord Lasike's status.
Our correspondent Katalina Tohi says further delays are now possible.
"And the motion of no confidence, they have not been able to do anything about it. And I am sure that Government would like to have a by-election because one of the nobles, the deputy chairman Lord Tu'iha'ateiho, will effectively become the acting Speaker of Parliament and that will leave only seven nobles representatives."
More than 3,000 people in Tonga have signed the petition expressing their opposition to a planned vote of no confidence in Lord Tu'ivakano's government.
The women's group, Fakatouhama, organised the petition and sought the backing of some MPs, who all refused to support it.
Its secretary, Dr. 'Ana Koloto has told Radio Tonga that the petition has come about because some people don't fully understand why the vote of no confidence is being sought.
Debate on the motion is set to resume today, after a series of delays.
It is the first time such an action has been taken in Tonga, which embraced a greater degree of democracy two years ago.