The group of 20 senators is led by Sawai Prammanee of Nakhon Ratchasima. "The EC should have all five members to take responsibility for the general election [slated for October 15]. We want the Constitution Court to rule on the case to help solve the political crisis," said Sawai.

But Suchon's comments last week that the three EC members should resign has the senators doubting whether the speaker will submit their petition. If he does not, they would go to the parliamentary ombudsman instead, Sawai said.

The ongoing controversy over the performance of the EC also presented the Supreme Court with a good opportunity to check on the remaining three commissioners, Sawai said.

EC chairman Vasana Puemlarp said earlier that he would resign when the two vacant EC positions were filled, as four commissioners would be enough to oversee the poll.

However, Buri Ram Senator Surapong Painual said that according to the Constitution, the Supreme Court must select the EC. But when the court refused to select other members, this caused further deadlock, he said. The senator questioned why the remaining three should resign when they had done no wrong.

Parliament should resolve the problem, he said.

Thai Rak Thai Party deputy leader Pongthep Thepkanchana yesterday said it would take the same length of time to find two or five election commissioners.

"It will take 35-40 days to pick the Election Commission," he said.

The Supreme Court had so far refused to find two new commissioners. But if the two remaining seats were filled, it would increase confidence in the EC's performance.