The move came ahead of a ruling today on whether the court will accept the cases accusing the two major political parties and three small ones of violating electoral law.

The senators alleged judges Suwan Suwanwecho and Jumpol na Songkhla are not neutral because they have close ties to Thaksin Shinawatra, the caretaker premier and Thai Rak Thai leader.

Suwan was a key leader behind a signature campaign supporting Thaksin while the Constitution Court was set to rule on an asset-concealment case against the newly elected premier in 2001, Chirmsak said. At the time, Suwan was an adviser to the PM's Office and secretary-general of the Police Association, he said.

When Suwan was nominated as a judge to the court last year, he told a Senate investigative panel that he had campaigned for Thaksin because it was appropriate for the police to support a former officer, Chirmsak said.

Chirmsak said Jumpol was among eight "majority" Constitution Court judges who acquitted Thaksin in 2001.

The senator alleged the judge helped Thaksin escape a "guilty" verdict in the controversial decision, citing testimony in late 2004 from Wasant Sroipisut, chief justice of the Region 7 Appeals Court. Wasant claimed that Jumpol asked him for advice on how to clear Thaksin of the allegation regardless of the evidence.

Jumpol said later the Constitution Court could have been burnt down by pro-Thaksin mobs had Thaksin been found guilty.

Jumpol said yesterday it would be up to the Commission of the Constitution Court's Judges to decide whether he should be involved in the cases. He said the 16 senators were "silly".

"The senators' allegations have no shred of truth," he said. "They are silly to make such accusations against me.

"Asking for Wasant's opinion did not mean that I would it as the deciding factor in the [asset-concealment] case," Jumpol said.

the nation