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.
Princess Ubolratana is slated to 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," he said.
However, Ubolratana's candidacy looked to be in trouble soon after it was announced, with King Maha Vajiralongkorn saying it was not appropriate.
"Involvement of a high-ranking member of the royal family in politics, in whatever way, is an act that conflicts with the country's traditions, customs, and culture, and therefore is considered extremely inappropriate," the king said in a statement from the palace.
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.
The commission is required to endorse all candidates by next Friday.
Paiboon Nititawan, leader of the People's Reform Party, which is close to the military, said on Friday that Ubolratana's candidacy could breach the Thai law banning political parties from using the monarchy for campaigning.
A royal in a populist party
The Raksa Chart Party is loyal to ousted prime minister and populist Thaksin Shinawatra. It is popular among the rural poor, but it is loathed by the military and the elite, including hardcore royalists.
Princess Ubolratana's nomination puts her up against Prayuth Chan-ocha, the current prime minister and formerly the country's top general. He announced he would run for re-election on Friday.
The military has traditionally been aligned with the royal family, but Princess Ubolratana's nomination could upend that.
The royal family is highly regarded in Thailand and carries great influence — especially in the case of recently deceased and longstanding King Bhumibol Adulyadej.
Many years in the US
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.
cmb/msh (Reuters, dpa, AP, AFP)