All Thai Raksa Chart (TRC) leaders planned to be at the Constitutional Court on Thursday afternoon for its ruling on the Election Commission's request it dissolve the party.
However, police were out in strong numbers to enforce a ban on public gatherings in and near the court compound.
TRC frontman Preechaphol Pongpanit said at the TRC head office all key members would travel to the court for the ruling at 3pm on the EC's case that the court disband the party
"We will go (to the court) and return together," he told reporters.
Executive members and key supporters would decide after the court decision what steps to take next, he added.
The EC accused the party of committing an act considered hostile to the constitutional monarchy in nominating Princess Ubolratana as its candidate for prime minister.
The party leader called for members and supporters to stay away and not go to the court, to avoid possible tensions.
"We do not want to see a situation that could result in trouble," he said.
Police have deployed 1,200 officers in and outside the court for security. The Metropolitan Police Bureau has issued an order banning public gatherings within a radius of 50 metres of the court.