Princess Ubolratana Rajakanya Sirivadhana Barnavadi, the sister of Thailand's current King Maha Vajiralongkorn, announced her candidacy Friday for prime minister in the upcoming elections on March 24.
The move was a first for Thailand, a constitutional monarchy since 1932 in which the royal family is expected to stay out of politics.
Assuming it goes ahead as scheduled this time, the upcoming March election will be the first since a 2014 coup installed a military junta, which promised a rapid democratic vote on seizing power.
Princess Ubolratana will run for the Thai Raksa Chart Party, an opposition group founded by the allies of former prime ministers Thaksin Shinawatra and his sister Yingluck, who was ousted in the coup.
"The party has nominated the princess as its sole candidate," party leader Preechapol Pongpanich told reporters after registering the princess as a candidate at the Election Commission. "She is knowledgeable and is highly suitable. I believe there will be no legal problems in terms of her qualification, but we have to wait for the Election Commission to endorse her candidacy," he said.
The commission is required to endorse all candidates by next Friday.
Princess Ubolratana is the elder sister of the current king. Born in 1951, she studied mathematics and biochemistry before earning a master's degree in public health, all in the US.
She relinquished her royal title in 1972 when she married an American. After living in the US for 26 years, she returned to Thailand in 2001 following her divorce. She has since performed royal duties but never fully regained her royal title.