BANGKOK (AP) — Hundreds of people gathered Sunday in the Thai capital of Bangkok to demand that conservative senators stop blocking the naming of a prime minister belonging to a winning coalition formed from May’s general election, a stance that risks a potentially destabilizing political deadlock.

Protesters braved heavy rain to show their anger and frustration toward the members of the Senate, who were appointed by the military and pride themselves as defenders of traditional royalist values, which they believe are under threat.

The surprise election winner, the Move Forward Party, failed in two efforts to have its leader Pita Limjaroenrat confirmed as the next prime minister, largely because he failed to woo enough votes from the senators, who are disturbed by the party’s reformist policy platform.

As many as 1,000 demonstrators took to Bangkok’s busy Asok intersection with umbrellas and raincoats. many shouting “Senators, get out!” Speakers at the peaceful rally also called for political parties in a coalition assembled by Move Forward not to “switch sides” by joining hands with other parties that supported the outgoing government of Prayuth Chan-ocha, who as army commander seized power in a 2014 coup and was returned as prime minister after the 2019 election.

Sombat Boonngam-anong, a veteran social activist who organized the rally, told the crowd that senators only have the right to vote yes, and described voting no as unconstitutional.

“You can only vote yes, because the people already said yes to the results. You don’t have the right to vote anything else,” he declared of the senators' responsibilities.

The Move Forward Party finished first in May’s general election and formed an eight-party coalition, which together won majority of 312 seats in the 500-member House of Representatives. But under the military-enacted constitution, a new prime minister must receive the support of a combined majority of both the lower house and the unelected 250-seat Senate.

Pita was rejected in a first vote and was knocked out of contention last when a procedural vote decided he could not be nominated a second time.

On Friday, the coalition held a meeting and announced that its second biggest member, the Pheu Thai Party, would nominate its candidate and assume the leading role in forming a government. Its three possible nominees are real estate tycoon Srettha Thavisin; Paetongtarn Shinawatra, the daughter of former Prime Minister Thaksin Shinawatra, who was ousted by a 2006 military coup; and Chaikasem Nitsiri, the party’s chief strategist.

While declaring that the coalition for now will stick with its original members and try to win more votes from conservative lawmakers before the next vote scheduled for Thursday, Pheu Thai did not rule out the possibility that Move Forward could be excluded from the coalition altogether in order for it to succeed in forming the government.

On Saturday and Sunday, Pheu Thai met with several parties that voted Prayuth in as prime minister in 2019.

The parties that met with Pheu Thai over the weekend, including the military-backed Palang Pracharath and United Thai Nation parties, while denying they discussed joining the coalition. also made it clear they would not be willing to do so as long as Move Forward remains in the bloc.

Some of Move Forward's supporters want the coalition to stand fast instead of inviting new members from the other side of the political spectrum, and feel their Pheu Thai colleagues are putting the pursuit for power ahead of principle.

Pheu Thai is the latest in a string of parties closely affiliated with populist billionaire Thaksin, who is in exile to avoid a prison sentence for abuse of power that he contends was politically inspired. Supporters of parties backed by Thaksin staged several mass protests against the conservative establishment that ousted him, spurring violent crackdowns, especially in 2010, when at least 94 people were killed.

Move Forward’s victory was powered by a widespread desire, particularly among young people, for deep structural change in Thailand after nine years of military-backed rule. The party also wants to reduce the influence of the military, which has staged more than a dozen coups since Thailand became a constitutional monarchy in 1932, and of big business monopolies.