Pressure continued to mount yesterday for the three election commissioners to resign their seats.

Songkhla activist Ekachai Isaratha yesterday threatened to launch an impeachment campaign against the three remaining members of the Election Commission (EC) if they refuse to resign by Monday.

EC chairman Vasana Puemlarp and commissioners Prinya Nakchudtree and Virachai Naewboonnien should resign before they are forced out of office, said Ekachai.

The Monday deadline coincides with the date of a Criminal Court ruling on whether to try the three on charges relating to the botched April 2 vote, he said.

He said he was confident he could gather the 50,000 signatures needed to activate impeachment proceedings within a month.

The Constitution requires the signatures be gathered within 180 days.

At the EC office, a group of senators submitted a letter signed by more than 30 senators that called on the EC trio to quit. The letter was handed to EC secretary-general Ekachai Warunprapa.

Among the senators present at the EC office yesterday were Somkid Sreesangkom, Somboon Thongburan, Charoon Youngprapakorn, Tuenjai Deetes and Nipon Wisityuthasart.

Senator Somkid said the commissioners should feel remorseful after their alleged mistake caused about Bt3 billion being wasted in holding the April 2 elections and subsequent rounds of voting.

He said if their request fell on deaf ears, the senators would seek a Constitution Court ruling on the EC members' status.

Meanwhile, Law Society of Thailand acting president Danai Anantiyo disclosed yesterday that the group last Friday petitioned the Ombudsman Office asking it to seek a Constitution Court ruling whether the EC members were qualified to retain their position.

He said the group's legal experts agreed the EC members failed to meet the required qualification that they must be politically neutral and completely honest.

In another development, Vasana, two colleagues and former EC member Charupat Ruangsuwan appeared before the Nakhon Si Thammarat Provincial Court for a hearing relating to the upcoming trial in which they are accused of dereliction of duty.

Vasana and the three other defendants were yesterday released on bail pending trial.

The defendants will fight criminal charges related to their decision last year to disqualify the ballot that elected Prayad Semapat mayor of tambon Pak Nakhon.

Prayad said he sued because he was disqualified in June, but the four defendants had not made their decision public until December, depriving him of a chance to appeal.

He has also filed a civil lawsuit demanding Bt100 million in compensation.