Political activist Srisuwan Janya lodged a complaint with the Election Commission (EC) on Wednesday after Senator Somchai Swangkarn posted screenshots of a WhatsApp chat believed to involve fugitive former prime minister Thaksin Shinawatra.
Screenshots posted on Mr Somchai's Facebook page on Tuesday showed an alleged conversation in which someone seeks advice from the former PM about a plan for the Pheu Thai Party to win the May 14 election. Even though the user's name appeared to be Thaksin Shinawatra, many people believe the chat is made up.
However, Mr Srisuwan said the chat was evidence of a violation of the amended Election Act for constituency and party-list MPs. He said only the EC can investigate and prove the chat illegal.
"This is my eighth time reporting suspicious acts from this person, but my requests were dismissed by the EC," Mr Srisuwan said. "I have emphasised that it was all connected. There is a mastermind behind the party."
Phumtham Wechayachai, deputy leader of the Pheu Thai Party, said on Wednesday he had seen screenshots of the WhatsApp chat, and it had nothing to do with his party. "Whoever is involved, let justice be done," he said.
Meanwhile, Paetongtarn "Ung Ing" Shinawatra, one of Pheu Thai's prime ministerial candidates, on Wednesday insisted a recent tweet by her father, Thaksin, will not affect the party's campaign or its popularity.
Thaksin on Monday wrote on social media that with his seventh and youngest grandchild being born, he would be back soon because, at the age of 73, he wants to be able to care for his grandchildren.
Ms Paetongtarn made her remarks after giving a statement about her newborn son, Prutthasin "Thasin" Sooksawas, at Praram 9 Hospital.
"I admit it's difficult to distinguish these things as Thaksin founded the now-dissolved Thai Rak Thai Party. Thaksin's only wish is to return home to raise his grandson, and he never said he wanted to become the prime minister again," said Ms Paetongtarn on Wednesday.
She urged people to understand how it would feel to be someone who has lived abroad in self-exile for 17 years.
"I'm happy that my father [Thaksin] said something like that -- to have hope of returning home, and staying healthy so he can see his grandson," said Ms Paetongtarn.
"Although every speech has an effect on politics, our family doesn't look at it that way. I have not talked to my father about when he will return, as he has his own plans. We've only talked about his grandson.''
Asked when she would continue canvassing, Ms Paetongtarn said she plans to be on Pheu Thai's campaign stage at Muang Thong Thani's Impact Arena on May 12.