A Thai political party on Friday named a princess as its nominee to be the next prime minister, upending tradition that the royal palace plays no public role in politics and upsetting all predictions about what may happen in next month's election.

The selection of 67-year-old Princess Ubolratana Mahidol by the Thai Raksa Chart Party marks a shock realignment of Thai politics, as she is now affiliated with a political machine that had been dismissed by hardcore royalists as opposed in spirit to the monarchy.

Her selection to lead the government after the March 24 general election also pits her against the preferred candidate of the military, which is considered one of Thailand's most royalist institutions.

Current Prime Minister Prayuth Chan-ocha, who led the 2014 coup that ousted Thailand's last elected government, on Friday accepted his selection as candidate to lead the next government by Palang Pracharat Party, widely considered a proxy for the military.

Ubolratana, whose official name is considerably longer than that under which she was registered with the Election Commission, is the first-born child of the late King Bhumibol and Queen Sirikit. Although seen as her father's favorite, she was virtually disowned by him in 1972 when she married an American who was a fellow student at the Massachusetts Institute of Technology. She lost two of her royal titles and lived in the United States, where she and her husband, Peter Jensen, had three children. Only after a divorce did she move back permanently to Thailand in 2001.

Since then she has thrown herself into charity work, especially her "To Be No. 1" foundation to fight youth drug abuse. She also frequently promotes Thai tourism and movies at international forums. In general, like most of the royal family, she publicly kept herself aloof from Thailand's recent political turmoil.

Thai politics for more than a decade has been shaken by violent street protests, coups and comebacks, but those are familiar events in Thai history. However, the death in 2016 of King Bhumibol Adulyadej added a major element of uncertainty, as he had served as a stabilizing force since taking the throne in 1946.

The other destabilizing element in Thai politics was the 2001 election as prime minister of telecommunications tycoon Thaksin Shinawatra.

His populist policies delivered him unmatchable electoral majorities, but he was resented by the traditional ruling class, including royalists and the military, and the army deposed him in a 2006 coup. Has been in exile since 2008 to avoid serving jail time on a corruption conviction he insists was politically motivated.

Thaksin's well-funded political machine returned to power twice since and is seen as the key element in arranging for Ubolratana's selection because she cast her lot with a Thaksin-affiliated party.

Most observers of Thai politics agree that Thaksin aggressively pursued good relations with Ubolratana's brother, current King Maha Vajiralongkorn, and friendship with the princess herself. These links were formed even as royalists and others loyal to the late King Bhumibol accused Thaksin of showing disrespect for the throne, and even of harboring secret republican tendencies.

When King Maha Vajiralongkorn, who has lacked the same level of devotion most Thais had for his father, ascended to the throne, conventional wisdom saw him as tightening his grip on power by allying himself closely with the military.

The surprise entry of his sister Ubolratana into politics — assumed to be with his blessing — raises questions about whether the long-lasting partnership of the palace with the army is in jeopardy.