The party will later this week send its letter to Senator John Kerry, chairman of the US Congressional Committee on Foreign Relations, to explain that Thaksin was behind the unrest and riots.
It also would point out that he was accused of terrorism in connection with the violence during the unrest in April and May 2010, the Democrat spokesman said.
Chavanont said the US government appeared to have changed its stance on Thaksin’s application for a US visa.
He said that when Thailand’s Democrat Party was in power, the US Embassy informed the Thai Foreign Ministry that Thaksin’s visa application to the US Embassy in the United Arab Emirates was rejected because the ex-leader was wanted for a serious crime under US law.