Mr Samak was elected in late 2007, but protesters want him out
Thailand's ruling party has abandoned its attempt to get embattled leader Samak Sundaravej reappointed as prime minister.
The People Power Party (PPP) had initially backed Mr Samak, who was stripped of office earlier this week.
But it became clear that coalition partners and some PPP lawmakers opposed the decision, and a planned vote to re-elect him could not go ahead.
The move could pave the way for an end to Thailand's political crisis.
Protesters have been demanding Mr Samak step down for weeks. They say he is a puppet for Thaksin Shinawatra, the former prime minister who the military accused of corruption and ousted in 2006.
Mr Samak had vowed not to bow to the protesters' demands, but was eventually forced out earlier this week over an appearance in a TV cookery show that a court said breached the constitution.
'Done his best'
The PPP initially said it would renominate him as prime minister, but early on Friday the vote to re-elect him had to be abandoned because too few MPs turned up.
26 Aug: Protesters occupy government buildings, demand the government step down
28 Aug: PM Samak promises no use of force against the protesters
30 Aug: Samak rules out resignation, after meeting with Thailand's king
1 Sept: A late-night clash between pro- and anti-government groups leaves one dead. Samak declares a state of emergency
4 Sept: Samak proposes a national referendum
9 Sept: Court orders Samak to resign for violating constitution
11 Sept: PPP re-nominates Samak as prime minister
12 Sept: PPP abandons move to re-elect Samak
It became apparent that partners in the ruling coalition and some members of his own party opposed his nomination.
A spokesman later confirmed that Mr Samak was no longer trying to win back his job.
"Prime Minister Samak asked me to deliver the message that he has done his best as the party leader to preserve democracy," his personal secretary Theeraphol Noprampha told journalists.
"Now his role has come to an end, and everything is now up to the party," he said.
Parliament is now scheduled to vote on a new prime minister on Wednesday.
So far no clear front-runner has emerged and the protesters, who are occupying government buildings in Bangkok, say they will not accept another leader perceived as close to Mr Thaksin.
But the choice of a compromise candidate could persuade the demonstrators to abandon the protests that have paralysed the government and driven tourists away, analysts say.
The PPP is expected to hold talks with the five other parties that make up the ruling coalition in the next few days.
The BBC's Jonathan Head, in Bangkok, says that whoever gets the job will face the unenviable task of calming the fevered political temperature and helping the governing party overcome some formidable challenges.
Over the next few months it must face the possibility of being dissolved by the increasingly assertive courts over allegations of vote-buying in the last election.