
Somchai has been working out of Chiang Mai since Wednesday, saying he wants to avoid a confrontation with the People's Alliance for Democracy, the group that has been campaigning since May to topple his government.
On Monday, Somchai went to a Buddhist temple in the northern city and prayed with dozens of monks for the health of King Bhumibol Adulyadej, the country's revered constitutional monarch who celebrates his 81st birthday on Friday. He also attended a royal flower exhibition.
Asked about the crisis, he told reporters: "The authorities are working in line with due process, but we have to depend on police, soldiers and civil servants." He refused to elaborate.
The protesters accuse Somchai of being a puppet of ousted Prime Minister Thaksin Shinawatra, the alliance's original target. Thaksin, who is Somchai's brother-in-law, was deposed in a 2006 military coup and has fled the country to escape corruption charges.
Alliance supporters are largely middle-class citizens who say Thailand's electoral system is susceptible to vote-buying and argue that the rural majority — the Thaksin camp's political base — is not sophisticated enough to cast ballots responsibly.
They have proposed discarding direct elections of lawmakers in favor of appointing most legislators, fostering resentment among rural voters.
On Monday, the alliance bused in more protesters to reinforce its siege of the Suvarnabhumi international airport and Don Muang. The reinforcements came from the prime minister's office compound, which the alliance had occupied since Aug. 26.
Protest leader Chamlong Srimuang said they were moving out because it was becoming unsafe to stay in the compound, which has frequently come under grenade attacks by unidentified assailants. A blast there Sunday wounded 49 people.
"We are not abandoning the site. We will end the siege at all sites at the same time," said Suriyasai Katasila, an alliance spokesman.
On Tuesday, a Constitutional Court will hear closing arguments in the electoral fraud case against Somchai's People's Power Party and two other parties in the governing coalition. A ruling could come as early as sometime this week.