Thailand’s Election Commission on Wednesday said it will ask the Constitutional Court to disqualify the party that nominated Thai Princess Ubolratana Rajakanya for prime minister, Reuters reported. The announcement followed an apology from the princess, who is King Vajiralongkorn’s older sister, on Tuesday.

The poll panel said that the Thai Raksa Chart party had violated a law and that its decision was “antagonistic toward the constitutional monarchy”. The party, however, has pleaded innocence in the matter and said it will ask the court to be “merciful”.

The court is likely to decide on accepting the case on Thursday.

On Tuesday, Ubolratana took to Instagram to apologise for causing an inconvenience to the people. “I am sorry my genuine intention to work for the country and Thai people has caused such problems that should not have happened in this era,” she said.

The development follows the Thai Raksa Chart party’s decision to pitch the princess as a prime ministerial candidate, a move that provoked a critical response from the king who referred to it as “highly inappropriate”.

Vajiralongkorn has said having the royal family in politics is against tradition. Soon after the king’s criticism, the party withdrew the princess’s name and cancelled a campaign event to comply “with the royal command”. The Election Commission also disqualified Ubolratana as a candidate.

Royals have not run for political office in Thailand since 1932.

Thailand is scheduled to hold its general election on March 24. The poll is likely to be a close contest between the military-backed royalist Prime Minister Prayuth Chan-ocha and supporters Thaksin Shinawatra, the brother of businesswoman and politician Yingluck Shinawatra and a former prime minister himself.

On February 9, the 67-year-old princess had said she wanted to run for office as she had relinquished all her royal titles and now lived as a common citizen. Ubolratana had given up her royal titles in 1972 after marrying an American. She returned to Thailand after a divorce. She has acted in films and is popular on social media.

The palace, however, maintains that she is still a member of the ruling dynasty. The king’s word is rarely ignored in Thailand.

The election is significant because it is the first since a successful coup against Yingluck Shinawatra’s government in 2014. Ubolratana’s candidature would have threatened the junta’s prospects, given her popularity. The party that fielded her is close to Thaksin Shinawatra.