The older sister of the king of Thailand said Friday she will run for prime minister in elections next month, upending the palace's decades-long tradition of eschewing politics and setting up a surprise contest with the leading military-backed candidate.
It pits her against the chief of the ruling junta and redrawing the nation's political landscape.
A group of people wearing colourful outfits pose for picture next to a large portrait of Thai King Maha Vajiralongkorn in Bangkok.
But while Ubolratana is afforded the same privileges, she has cultivated a more accessible image than her reserved younger brother and shown a knack for reading the sentiments of ordinary Thais.
But the monarchy could now be seen as effectively aligned with Thaksin's populist political movement, and if Ubolratana is to become prime minister, it could also pave a path forward for the return of the Thaksin family to Thailand.
The King said: "Involving a member of the royal family in politics is considered as going against tradition and culture, and is seen as extremely inappropriate".
"The king and royal family exist in a status above politics", said the statement, published in the Royal Gazette and given blanket television coverage.
On Thursday, Ubolratana's latest Instagram post generated debate, as rumours swirled that she had agreed to stand as a prime ministerial candidate.
Pro-democracy demonstrators shout slogans during a rally to protest the possible delay of the general election in Bangkok. "Who would dare criticise a royal prime minister?"
"I want to clarify that I have relinquished the rank of nobility and am living as a commoner".
The other destabilizing element in Thai politics was the 2001 election as prime minister of telecommunications tycoon ThaksinShinawatra.
"Royalists who had been appalled by the prospect of a political deal with Thaksin are now rejoicing, while Thais who believed the deal heralded an end to political conflict are now heartbroken", he said in a statement.
It also potentially bridges the political divide between the "Red" shirted loyalists to Thaksin and the "Yellow" shirted royalist supporters, whose violent clashes have scarred Thailand's recent history. Has been in exile since 2008 to avoid serving jail time on a corruption conviction he insists was politically motivated.
The decision by a party linked to former premier Thaksin Shinawatra to nominate her marks a monumental shift for Thailand, where the royal family is officially treated as semi-divine and apolitical.
"I maintain that I have no intention to prolong my power in office".
Ms Ubolratana's candidacy was questioned by a small pro-military party, the People's Reform Party, which asked the Election Commission to consider whether it violated laws forbidding parties from invoking the monarchy in campaigns.
The sister of Thailand's King Maha Vajiralongkorn has joined the race to be the country's next prime minister.
But after their divorce she returned home to Thailand, where officials treat her as a member of the royal family.
In short: Can they criticize her without running afoul of Thailand's laws?
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.
"From my point of view, I think she understands Thai politics".
"This is a profound development that will shape the contours and dynamics of Thai politics before and after election".
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 vastly wealthy Crown Property Bureau is now under his personal stewardship, he has appointed several new privy counsellors and established a highly trained personal guard.
He is a former army chief who led the 2014 military coup that ousted the country's last elected government, led by Yingluck Shinawatra.
His coronation will be held in May.