Khan Said, also known as Sajna, has been appointed the new head of the Pakistani Taliban after Hakimullah Mehsud was killed in a suspected US drone strike.
Said was appointed by the Shura, or consultative body of the Tehreek-e-Taliban Pakistan (TTP), on Saturday, after getting 43 of 60 votes.
Sajna was previously responsible for TTP operations in South Waziristan, and a trusted lieutenant of Mehsud.
Mehsud's death on Friday came at a crucial moment in Pakistan's efforts to end the group's bloody six-year insurgency that has left thousands of soldiers, police and civilians dead.
We can say that this time drone struck the peace talks but we will not let the peace talks die.
Prime Minister Nawaz Sharif had been expected to send a delegation to open contacts with the group, after winning backing for dialogue from political parties last month.
Security forces were put on red alert after the attack just outside Miranshah, the capital of North Waziristan province, bordering Afghanistan.
Al Jazeera's Imtiaz Tyab, reporting from Islamabad, said authorities were bracing for reprisal attacks by the TTP.
"The Pakistani Taliban hasn't said that they're going to strike back but it would be surprising if they didn't. This is a group which is known for carrying out extraordinary attacks on the civilian populous," he said.
The Pakistani Taliban was behind some of the most high-profile attacks in Pakistan in recent years, including the 2008 bombing of the Islamabad Marriott hotel and the attempt to kill schoolgirl activist Malala Yousafzai last year.
Officials said Mehsud was killed after attending a gathering of 25 Taliban leaders to discuss the government's offer of talks.
Information Minister Pervez Rasheed said the government would not allow his death to derail proposed peace talks.
"We can say that this time drone struck the peace talks but we will not let the peace talks die," Rasheed said.
No formal talks have begun and opposition parties accused the US of using the drone strike to stymie the process before it had even started.
Former cricketer Imran Khan, leader of the Pakistan Tehreek-e-Insaaf (PTI) party that rules in northwestern Khyber Pakhtunkhwa province, said the strike had "sabotaged" peace talks.
"It has proved that they do not want peace in Pakistan," said Khan, adding that PTI would move to block the transit of NATO supplies through Khyber Pakhtunkhwa to Afghanistan.
Jan Achakzai, spokesman for the key Jamiat Ulema-e-Islam Fazl (JUI-F) religious party whose head Fazlur Rehman is helping government in contacts with Taliban, also condemned the attack.
"It is a setback for a peace camp in Pakistan. The drone attack has been carried out a time when there was an enabling environment for peace talks and despite the Americans saying they supported the internal reconciliations," he told the AFP news agency.
As leader of the Pakistani Taliban, Mehsud was the most wanted man in Pakistan and the US had a $5m bounty on his head. He was believed to be in his mid-30s.
He was believed to have been behind a deadly suicide attack at a CIA base in Afghanistan, a failed car bombing in New York's Times Square and other brazen assaults in Pakistan that killed thousands of civilians and security forces.
Mehsud, who had been reported dead several times before, became the leader of the Pakistani Taliban in August 2009 after a drone strike killed Baitullah Mehsud, the group's previous leader and Hakimullah's mentor.
The Pakistani Taliban acts as an umbrella for various jihadist groups who are separate from but allied to the Afghan Taliban.
Mehsud's death is the third major blow struck against the TTP by the US this year, after the killing of number two Wali-ur Rehman in a drone strike in May and the capture of another senior lieutenant in Afghanistan last month.