Nawaz Sharif was ousted after a top court sacked him after an investigation into corruption allegations against him and his family, ending his third term in power.
Ousted Pakistani Prime Minister Nawaz Sharif began a rally on Wednesday in a defiant show of political power after a Supreme Court decision disqualified him from office late last month over undeclared assets.
Sharif launched the "caravan" from Islamabad to his eastern hometown of Lahore despite concerns of close advisers about security for himself and the crowds he is expected to attract, local media reported.
Thousands of Sharif party supporters thronged the capital to take part in the rally, setting up camps all along the route Sharif is expected to take and address supporters.
"Nawaz Sharif is still our prime minister," said worker Niaz Ahmad, who wore a lion look-a-like dress, chanting, "Lion, lion!" Lion is Sharif's political party election symbol.
Sharif was seen off in Islamabad by the new prime minister, Shahid Khaqan Abbasi, the new cabinet and other party officials, said Sharif's political adviser Asif Kirmani.
"We really don't know how long it will take, how many days, we have no idea," Kirmani told reporters. He said a huge number of people were waiting for Sharif all along the Grand Trunk Road, that runs between the capital Islamabad and Lahore city. The two cities are about 380 km (237 miles) apart.
Sharif, 67, resigned swiftly from his third stint as prime minister after the Supreme Court's five-member panel ruled on July 28 that he should be disqualified. The court also ordered a criminal probe into the Sharif family over allegations stemming from the Panama Papers leaks of international offshore companies.
Sharif in recent meetings with party leaders, lawyers and media has expressed his displeasure over the court ruling.
He said that no corruption was proved against him, and that it was unfair to sack him on the basis that he didn't declare a salary from his son's Dubai-based company in assets submitted to contest the 2013 elections that brought him to power.
Sharif's ruling Pakistan Muslim League-Nawaz (PML-N) party, which has a solid majority in parliament, elected his close aide Abbasi as his replacement within four days.
The party leaders have suggested in recent days that Abbasi is expected to hold office until elections due next year against an initial decision that Sharif's younger brother, Shahbaz, would take over the office.
Shahbaz is now likely to replace his brother as party chief, since the ousted premier is no longer eligible to lead a political party under a Pakistani law that bars any convicted or disqualified person from such a role.
The opposition party of cricket-star-turned-politician Imran Khan has challenged Nawaz Sharif's party leader status in a court.