Their ban expired on Monday and they were welcomed on Thursday by party leader Theera Wongsamut.
Banharn said he has no suggestions about the political turmoil and would not help to find a solution to the current conflicts, as no one listened to him.
He added that he hoped that all parties would take a middle way out of the political conflict.
Asked about a royally appointed prime minister, as invoked in Article 7 of the Constitution, he said that it would disturb the King.
“I want Thailand to be like Japan, which is able to end all problems by a House dissolution. However, the protesters have said the resignation of the prime minister and a House dissolution is not enough to satisfy them, so I don't know what the solution can be to end the current conflicts," Banharn said.