Seven pro-democracy political parties in Thailand have united to form a coalition large enough to claim a parliamentary majority and declared their intention to form a government, ousting the military from power.

The announcement came amid concerns about potential irregularities in Sunday’s vote and before a full preliminary vote count has been released. Official results are not due until May.

Thailand’s Pheu Thai party said on Wednesday that it had formed a “democratic front” with six other parties after the disputed election, claiming the opposition alliance had won a majority in the lower house of parliament and the right to try to form a government.

The coalition, led by Thaksin-aligned party Pheu Thai which won the most seats in Sunday’s election, said they intended to “bring back democracy and stop the power of the NCPO [military junta]”.

Pheu Thai leader Sudarat Keyuraphan said that between the seven parties who had united as part of a “democratic front”– Pheu Thai, Future Forward Party, Thai Liberal Party, Phea Chart Party, Prachachat Party, Thai People Power and New Economic Party– had 255 seats between them, enough to secure a majority in 500-seat house of representatives and form a government.

“Right now are are starting with seven parties,” said Sudarat. “We want to demonstrate that our goal is to stop NCPO power, then we will discuss with other parties to help us. But we already have a majority.”

The official result of the election, Thailand’s first since the military took over in a coup in 2014, still remains uncertain after the election commission postponed the announcement multiple times for reasons still unexplained, leading to allegations of foul play and ineptitude. They now are not expected to announce the result until 9 May.

Sudarat said the election process had been “questionable”, with “a lot of vote buying, intervention of state influence… the counting of the votes was abnormal”. The leaders of the coalition parties said they would be visiting the election commission on Wednesday afternoon to demand transparency around the election results, which have yet to be released.

She added: “Last time the military took power through a coup, this time they are trying to do it through manipulation. Our main mission is that we don’t want any more chaos. We want to move forward following the people’s voice. We got the majority so we will proceed to stop the NCPO.”

In the absence of an official winner, both Pheu Thai and the pro-military party Phalang Pracharat, which was formed by the junta as a way to hold onto power through the ballot box, have claimed victory in the election. While Pheu Thai won the most parliamentary seats, Phalang Pracharat won the popular vote, which they claim gives them legitimacy to govern.

The parliamentary system already favours returning the military to government, due to a new constitution drawn up by the junta in 2016, which gave them the power to appoint all 250 senators in the upper house, who get a vote on who becomes prime minister.

With all 250 seats in the upper house all but guaranteed to favour the pro-military choice for prime minister, the pathway is set for the return of the head of NCPO, Prayut Chan-ocha, as prime minister.

But speaking at a press conference, the pro-democracy coalition demanded that the prime minister come from the party which had the most parliamentary seats, reflecting the “voice of the people”, and were adamant the senate should not be involved in selection.

“We insist that the prime minister should come from the first nomination of the party that gained the highest vote, so I support Sudarat” said leader of Future Forward party Thanathorn Juangroongruangkit. “This current situation is not democracy. It’s not to the benefit of the country. We need to prioritise the voice of the people and stop the NCPO holding on to power.”

Thanathorn directed his criticism at the attempts by Phalang Pracharat to also form a coalition. “I urge another side who is trying to form a government from the minority vote to stop,” he said. “It will only lead to deadlock”

However, even with the pro-democracy coalition claiming they have 255 seats, until the election commission confirm the results, nothing can be confirmed.

Sudarat voiced concern that the pro-military faction may try and pressure or “lure” MPs from their side to join their coalition over the coming days “using benefits or positions” or would disqualify pro-democracy MPs to reduce their numbers.

On Wednesday, the Phalang Pracharat spokesperson Thanakorn Wangboonkongchana said the party was still “confident we will collect the majority votes in order to form the government.

“We have been in discussion with other parties,” said Thanakorn. “We have the right to form the government support Prayut as prime minister.”