
Apirak Kosayodhin, the Democrat Party candidate, resigned as governor after the National Anti-Corruption Commission charged him with illegally opening a letter of credit to buy fire engines.
Prapat said now that Apirak was out, he stood a better chance of winning, but he would not like to break his vow with his family.
Wattana Sengpairoh, who is in charge of the PPP's Bangkok election, said the party would invite Kittiratt Na Ranong - the former president of the Stock Exchange of Thailand who once offered to work with the party - to be its candidate.
However, nominations were still open to interested outsiders, he said.