The JUI-F march is supported by main opposition parties like Pakistan Muslim League - Nawaz of former premier Nawaz Sharif and Pakistan Peoples' Party of former president Asif Ali Zardari as well as nationalist and secular parties.
Thousands of supporters of a religious political party took part on Sunday in an anti-government procession headed to Pakistan's capital.
Mufti Abrar Ahmed, spokesman for the Jamiat Ulema-e-Islam-Fazal (JUI-F) party, said a caravan of hundreds of buses and vans that originated in the southern port city of Karachi will make its first overnight stop in Sukkur in Sindh Province.
Before departing Karachi, JUI-F chief Maulana Fazlur Rehman told the massive gathering that the procession is also a way to show solidarity with Kashmiri residents facing hardship at the hands of Indian troops. He said the nation is one in support of oppressed Kashmiris.
The beginning of the JUI protest also marks the anniversary of the start of the conflict over Kashmir, a region both India and Pakistan claim. Separately, anti-India protests were planned across Pakistan.
Rehman said the march was also meant to call for the removal of Pakistan's "illegitimate" government, which he claimed was imposed on the nation by "stealing the people's vote."
The march was being supported by main opposition parties like Pakistan Muslim League of former premier Nawaz Sharif and Pakistan Peoples' Party of former president Asif Zaradri. Nationalist and secular parties also backed the protest.
Ahmed said supporters from Karachi and surrounding areas was expected to reach Islamabad on October 31 to protest Prime Minister Imran Khan's "illegitimate" government, which the right-wing party says came to power through the army's support.
Khan's government negotiated with organisers of the protest to contain them in a certain part of the capital. But the administration has a security plan in place with shipping containers placed aside the roads and additional riot police will be deployed.