Opposition leaders announced plans to block major highways, halt traffic and suspend the fuel supply from the southern port city of Karachi late Tuesday night.
Members of Jamiat Ulama-e-Islam Islamic party led by an influential cleric, Maulana Fazlur Rehman, captured a major highway in Islamabad on Nov. 1.
“We are now going for plan B and will not stop before throwing out illegal government,” Rehman said in a speech to his cheering supporters.
Rehman, a 66-year-old Sunni Muslim, was leading the protests with his followers mainly from the Islamic schools.
Other parties including that of former premier Nawaz Sharif have also been taking part in the protests but their presence has been thin.
The opposition said last year’s elections that brought Khan to power were rigged by the military to install a government of the generals’ choice.
The military has ruled Pakistan for almost half of its existence since the country gained independence from Britain in 1947.
Opposition parties said they would seek fresh elections without manipulation by the military.
The opposition parties have also begun an impeachment process against the deputy speaker of the parliament, a close aid of Khan, with voting expected in a couple of weeks.