Selina Downes, Al Jazeera's correspondent in Bangkok said the prime minister has been holding high-level crisis talks with members of the military and said he had not ruled out initiating a state of emergency.
"I will not quit. At this moment, I will not declare emergency rule, I will wait and see tomorrow," Samak said on Friday.
Al Jazeera's Downes said Samak was likely to wait until after Saturday when Thailand's crown prince is due to make a speech.
"The crown prince may call for unity, and the royal family are highly regarded here," which may quell some of the protests, Downes said.
Samak briefed King Bhumibol Adulaydej on the anti-government protests late on Friday at the seaside resort of Hua Hin.
He was set to meet Maha Vajiralongkorn, the crown prince, on Saturday.
Thailand's ruling six-party coalition has, meanwhile, agreed to hold an urgent parliamentary debate on Sunday to discuss the continuing crisis.
Protesters have reportedly overrun parts of Government House and closed three airports in the southern tourist destinations of Phuket and Krabi.
Downes said: "People are saying about 1,000 protesters sealed-off roads going into and out of the airports.
"Thai airways' labour and electricity unions have also said they will join strikes calling form the prime minister to resign."
State rail workers had begun a strike that had halted 30 per cent of services nationwide, a union spokesman said, and similar action was being considered by unions at other state agencies.
"The prime minister has said to the protesters: 'You are called the People's Alliance for Democracy, so what is it you want? Because the key element of democracy is elections'," Downes reported.
Call for emergency
In the capital, where protesters have been occupying the prime minister's compound since Tuesday, some of Samak's advisers have urged him to impose emergency rule, two government sources said.
A state of emergency would allow the government to deploy soldiers to disperse the protesters. But Anupong Paochinda, Thailand's army chief, said the situation does not currently warrant it.
|Thai activists launched street campaigns against Samak on May 25 [AFP]
Police appeared to exercise restraint when the protesters, some armed with golf clubs, batons and bamboo sticks, forced 400 personnel out of the government house grounds early on Friday morning.
Downes said crowds appeared to be provoking police action, but the government was still withholding the use of force.
Samak and police officials have repeatedly said that force will not be used to remove the thousands of protesters.
Police Lieutenant-General Suraphol Thuanthong said that they will use a "softened stance [to] give them time to leave the government house".
"But if they continue to defy the court order, then we have to use force to drive them out," he said.
The PAD, whose 2005 protests against Thaksin contributed to his removal in a coup a year later, urged more supporters to gather until the current elected administration fell.
"Today is the judgment day. It is the people's revolution and we must win," Sondhi Limthongkul, a PAD leader, told the cheering crowd from the group's constructed stage on the prime minister's front lawn.
Nine PAD leaders have been charged with insurrection, a crime that can carry the death penalty, after violent raids on government offices and a state TV station on Monday.