Thailand’s wait for a new prime minister after the May general election may get longer as the nation’s ombudsman plans to challenge a parliament move to deny renomination of pro-democracy leader Pita Limjaroenrat.

The Office of the Ombudsman plans to petition the constitutional court to delay a fresh vote to select a prime minister until it rules on the legality of the parliament’s decision against Pita, Secretary-General Keirov Kritteranon told a briefing on Monday. The move follows a clutch of petitions from lawmakers and legal experts seeking the ombudsman’s help in approaching the court, he said.

A majority of Thai lawmakers voted against Pita’s bid to be nominated as the prime ministerial candidate for a second time after he lost a vote a week earlier. The leader of Move Forward Party lost his first premier vote after pro-royalist parties and members of the conservative Senate voted against him, citing their opposition to his party’s pledge to amend the royal insult law which which penalizes criticisms against the monarchs.

The parliament decision, slammed by Pita’s camp as unconstitutional, forced Move Forward to make way for its alliance partner Pheu Thai to take the lead in government formation. But the ally, linked to former premier Thaksin Shinawatra, is under pressure to snap ties with Pita’s party in exchange for support from the Senate and the conservative parties.

The delay in government formation has weighed on Thailand’s stocks with foreign investors pulling out more than $3.3 billion this year. The political gridlock is a key reason for souring business outlook over the next three months, the Federation of Thai Industries said on Monday.

Senator Kittisak Rattanawaraha said on Monday that members of the upper house may support Pheu Thai’s efforts to form the government, provided it doesn’t involve Move Forward.

The pro-democracy alliance is scheduled to meet on Tuesday, and the ombudsman’s move to seek a charter ruling may prevent an immediate implosion of the coalition.

While parliament has scheduled the next prime minister vote on July 27, Pheu Thai has yet to announce who it would pick as its nominee from prime minister from among its three candidates that include property tycoon Srettha Thavisin and Thaksin’s youngest daughter Paetongtarn Shinawatra.

Leaders of conservative parties — Bhumjaithai, Palang Pracharath and United Thai Nation — told Pheu Thai executives at the weekend that they will not support its candidate as long as Pita’s party remains part of the alliance.

“Conservatives seem to have designed several plans to create bad outcomes for society if Pheu Thai still remains with Move Forward,” said Siripan Nogsuan Sawasdee, political science professor at Chulalongkorn University. “The bottom line is to cut off Move Forward, not just Pita.”