The Pakistan Army on Saturday took control of the security of polling stations ahead of Sunday's by-polls for 11 national and 24 provincial seats.
Final preparations were underway to conduct elections in nine National Assembly constituencies in Punjab and one each in Sindh and Khyber Pakhtunkhwa, and 24 provincial assembly seats, including 11 in Punjab, nine in Khyber Pakhtunkhwa and two each in Sindh and Balochistan.
Most of these seats were vacated by the candidates who won from more than one seat in the general elections held on July 25.
Prime Minister Imran Khan won five seats and vacated four which are also up for grabs.
For the first time, overseas Pakistanis will participate in the election process through a special online portal designed by the Election Commission of Pakistan (ECP).
Thousands of soldiers will stand guard to provide security at 7,489 polling booths to ensure a smooth and peaceful electoral process.
The ECP, while making security arrangement, designated as many as 1,727 polling stations "highly sensitive" where extra troops were deployed and security cameras installed.
These include 848 out of total 5,193 polling stations in Punjab, 544 in Khyber Pakhtunkhwa, 201 in Sindh and 134 in Balochistan provinces.
The deployment of troops began on Friday and they would remain on election duty till October 15.
Soldiers will be deployed inside and outside the polling stations in order to avoid any untoward incident.
They also provide security during distribution of election material and transportation.
Designated army officers have powers of a magistrate first class for summarily trial of those guilty of impersonation, capturing polling stations or violation of other relevant provisions of the law.
The ECP said 9.28 million voters are eligible to exercise their franchise in 35 constituencies.
The polling will start at 8am and will continue without any break until 5 PM (local time).
A tough competition is expected between the ruling Pakistan Tehreek-e-Insaf (PTI) and the main opposition Pakistan Muslims League-Nawaz (PML-N).
Former prime minister Shahid Khaqan Abbasi and some ministers are also taking part in the contest.
Abbasi, who was defeated from Rawalpindi and Islamabad, is contesting from a secure seat, NA-124 in Lahore, which the PML-N has never lost.
Meanwhile, the PML-N and Pakistan Peoples Party (PPP) announced to support each others' candidates through seat adjustment. The two parties have also reached an understanding with the Jamiat Ulema-e-Islam Fazal of Maulana Fazlur Rehamn.
