Pakistan is to review its relationship with the United States, the prime minister's office said on Sunday, following the killing of the Pakistani Taliban leader in a U.S. drone strike.
But a top-level meeting to examine relations, scheduled for Sunday, was postponed at the last minute without explanation.
Mehsud, who had a $5 million U.S. bounty on his head, was killed on Friday in the northwestern Pakistani militant stronghold of North Waziristan, near the Afghan border.
The Pakistani Taliban have killed thousands of Pakistani civilians and members of the security forces in their bid to impose Islamist rule, but the new government has been calling for peace talks.
The government denounced Mehsud's killing as a U.S bid to derail the talks and summoned the U.S. ambassador on Saturday to complain.
Prime Minister Nawaz Sharif's office had said he would chair a meeting on the consequences for ties with Washington. There was no indication when it might now take place.
Some politicians have demanded that U.S. military supply lines into Afghanistan be blocked in response.
"It is clear that the U.S. is against peace and does not want terrorism to subside. Now, we only have one agenda: to stop NATO supplies going through (the northern province of) Khyber Pakhtunkhwa," Asad Qaiser, the speaker of the provincial assembly, told Reuters.
Pakistan is the main route for supplies for U.S. troops in landlocked Afghanistan, for everything from food and drinking water to fuel, and the closure of the routes could be a serious disruption as U.S. and other Western forces prepare to withdraw from Afghanistan by the end of next year.
Pakistani cooperation is also seen as vital in trying to bring peace to Afghanistan, in particular in nudging the Afghan Taliban, allied but separate from the Pakistani Taliban, into talks with the Kabul government.
Relations between the United States and Pakistan have been seriously strained several times over recent years, including in 2011, when U.S. forces killed al-Qaida mastermind Osama bin Laden in a raid that Pakistan said violated its sovereignty.
But cash-strapped Pakistan depends to a great extent on U.S. support. Washington, despite frustrations over the relationship, is unlikely to break completely with its nuclear-armed ally.
Three Pakistani Taliban commanders said they had been due to meet a government delegation on Saturday and they had been meeting to discuss the talks. They said they felt betrayed by Mehsud's killing and were not interested in talks.
A Pakistani Taliban spokesman vowed a wave of revenge bombings. Allied militant groups are also planning bombings, said Ahmed Marwat, the spokesman for Jundullah militant group. The group recently killed more than 80 people when it bombed a church and is known for big attacks on civilian targets.
Mehsud's followers have been debating who should replace him while they observe three days of mourning, said Taliban spokesman Shahidullah Shahid. They have in the meantime appointed an interim leader, Asmatullah Shaheen.
Several militant commanders said on Saturday that 38-year-old Khan Said, known as Sajna, had been chosen.
But other factions of the Pakistani Taliban alliance were unhappy with the choice and were supporting other candidates. These included Mullah Fazlullah, the ruthless commander from the Swat Valley, northwest of the capital, Islamabad, whose men shot and wounded schoolgirl Malala Yousafzai last year.
Said was seen as a relative moderate and if he became leader, talks with the government might eventually get going, said Imtiaz Gul, head of Islamabad-based Center for Research and Security Studies
But if Fazlullah was chosen, there would be little hope of compromise, he said. Even if talks started, it was unclear how successful they would be unless the government gave significant concessions to the militants.
"You're compromising the rule of law, and ceding ground to non-state actors, giving in to a small band of criminals. It threatens everything on which Pakistan stands - the constitution, parliament," Gul said.
"They haven't thought through the consequences of these talks. They're just firefighting because they have no long-term remedy for Pakistan's problems."
While the government has been promoting talks, some in the the powerful military have privately voiced their opposition to negotiating with the al-Qaida-linked militants.