A stridently anti-military Thai party survived a first legal attempt to disband it over alleged sedition.
The runners massed before dawn in a Bangkok park to take a stand against the government.
The Run Against Dictatorship rally in Bangkok is set to attract thousands of supporters and participants.
Two opposing events will take place at the same time, approximately 11 kilometres apart.
A recent NIDA Poll named Thanathorn as number one choice for Thai Prime Minister.
Last Saturday, Thailand saw its largest street protest in more than five years.
Thousands rallied in Bangkok behind the popular leader of an upstart anti-establishment party on Saturday.
Five other leaders from Thailand's opposition bloc were also charged, as well as several academics.
Thailand's constitutional court suspends Future Forward leader from parliament.
Billionaire charismatic leader of Thailand’s third largest party is being persecuted by the military junta.
Future Forward is a key part of a coalition trying to prevent the junta’s proxies from forming the next government.
A survey of 32 Thai political parties earlier this month found that human rights is not a critical issue for them.