A member of Thailand's Election Commission said it may prove impossible to complete this month's disrupted election and the whole vote may need to be re-run.
This could lead to many months more under a caretaker government with limited powers.
Action by anti-government protesters meant voting was scrapped or halted in about a fifth of constituencies, so there will not be enough politicians elected to convene parliament to vote in a prime minister.
"If the situation continues like this, there is no way the election will be successful and we will not get the 95% of parliamentary seats needed," Election Commissioner Somchai Srisutthiyakorn said.
"We might have to sacrifice this election and call a new one... The government will have to call a new election date and get the king's endorsement," he said.
According to Mr Somchai's reading of the constitution, voting has to be held on the same day throughout the country, so holding fresh votes would be illegal.
The government contests that and wants the five-member Commission to ensure voting in the affected constituencies goes ahead as soon as possible.
Mr Somchai doubted that was on the cards, given the opposition of the protest group, the People's Democratic Reform Committee(PDRC), which wants political and electoral changes implemented before an election and rejected the 2 February ballot.
"I've been to 12 out of 14 provinces in the south and the PDRC down there really won't cooperate. They are really against an election," he said.