BANGKOK, Thailand — Thailand’s new prime minister has shown his determination to mend political rifts by quickly shaking hands with the opposition leader. But the gesture did not appease anti-government protesters, who called him unfit for the job because of ties to a disgraced former leader.

A 61-year-old former judge, Somchai Wongsawat, is known as a conciliator, in sharp contrast to his combative predecessor — and the protesters’ original target — Samak Sundaravej, whom a court forced from office last week for taking pay to host TV shows.

The new leader appealed for unity during a news conference after his election today.

“It is now time for Thailand to unite, to reconcile and to solve the conflict,” Mr. Somchai said. “It is not unusual to be angry, but we have to work together to make Thailand peaceful again.”

Mr. Somchai carries heavy baggage, however. He is married to the sister of Prime Minister Thaksin Shinawatra, who was ousted by a 2006 coup amid corruption allegations. And he is deputy leader of the ruling People’s Power Party, which was formed by Mr. Thaksin’s allies.

The new prime minister “might have a gentlemanly nature, a soft-spoken style, and he might have a better reputation than everyone else (in the ruling party), but blood is thicker than water,” a leader of the protesting People’s Alliance for Democracy, Somsak Kosaisuk, said. “Thaksin needs someone he can control.”

Drawing loud cheers from protesters camped on the grounds of the Government House complex, Mr. Somsak said the sit-in would continue until the “remnants of Thaksin’s regime are gone.”

The alliance, which had called Mr. Samak a puppet of Mr. Thaksin, charges that Mr. Thaksin used his personal wealth to corrupt politics during his years as prime minister and then benefited from his high office.

Mr. Somchai, who was deputy prime minister and education minister in Mr. Samak’s seven-month government, easily won on a 298-163 vote in the lower house of Parliament, backed by the six parties in the governing coalition. His selection still needs formal approval by Thailand’s king.

After a brief statement to lawmakers promising to do his best to carry out his duties, Mr. Somchai strode across the chamber to shake hands with a Democrat Party leader, Abhisit Vejjajiva, the leader of the opposition.

The Democrats have shown some sympathy with the protest alliance, and one of its lawmakers has a prominent role in its leadership.

Rank and file members of the People’s Alliance for Democracy rejected Mr. Somchai.

One protester, 40-year-old Chansi Onsithan, said she was prepared to stay camped on the prime minister’s muddy lawn. “We won’t leave until he leaves. If he wants to stay for four years, fine, we’ll stay here for four years.”

Thousands of supporters of the protest alliance stormed the Government House on Aug. 26 with the goal of kicking Mr. Samak out of office. They now say that any member of the ruling party, which is full of Thaksin allies, is unacceptable as prime minister.