Asked when this would be, he said: "We have to wait, wait for the announcement." The election will again pit the billionaire Shinawatra family against parties backed by the military and old money conservatives, in what has been a bitter, 18-year power struggle in Southeast Asia's second-biggest economy. Prayuth, a retired general who has been in charge since leading a coup against the government of Yingluck Shinawatra in 2014, will run under the new United Thai Nation party. He will be up against Paetongtarn Shinawatra, the daughter of former premier Thaksin Shinawatra and Yingluck's niece. Paetongtarn, 36, has led Prayuth in opinion polls for months on the top choice for Thailand's next prime minister. (Reporting by Panarat Thepgumpanat, Panu Wongcha-um and Juarawee Kittisilpa; Writing by Martin Petty; Editing by Frances Kerry) Disclaimer: This report is auto generated from the Reuters news service.