ISLAMABAD, Aug 21: The country`s biggest-ever byelections in 41 national and provincial assembly constituencies will be held on Thursday an exercise seen by many as a test of popularity graph of key political parties.

According to the Election Commission of Pakistan, 519 candidates will contest for 41 seats 15 of National and 26 of provincial assemblies.

Most of the seats have been vacated by the winners of more than one seat, while others have fallen vacant because of disqualification of candidates by superior courts.

Elections in some constituencies were not held on May 11 due to death of candidates.

At the request of the ECP, the army has already deployed its troops in and around `highly sensitive` polling stations. The army personnel will perform duty outside those polling stations which have been declared `sensitive` In most of the constituencies, a neck-and-neck contest is expected between candidates of ruling PML-N and Pakistan Tehreek-i-Insaf (PTI).

The PPP is believed to be at number three in the contest.

The PML-N and the PPP have not fielded their candidates for any provincial assembly seat in Khyber Pakhtunkhwa.

Similarly, no candidate of the N-League is contesting for any provincial assembly seat in Sindh.

NA SEATS: The National Assembly constituencies where by-elections will be held include NA-1 (Peshawar), NA-5 (Nowshera), NA13 (Swabi), NA-25 (D.L Khan-cum-Tank), NA-27 (Lakki Marwat), NA-48 (Islamabad), NA-68 (Sargodha), NA-71 (Mianwali), NA83 (Faisalabad), NA-129 (Lahore), NA-177 (Muzaffargarh), NA-235 (Sanghar), NA-254 (Karachi) and NA262 (Killa Abdullah).

NA-1 and NA-71 seats have been vacated by PTI chief Imran Khan who chose to retain NA-56 (Rawal-pindi). Mr Khan had contested for four NA seats and lost only one in Lahore to incumbent National Assembly Speaker Sardar Ayaz Sadiq.

The NA-68 seat has been vacated by Prime Minister Nawaz Sharif who retained his home constituency (NA120 Lahore).

NA-129 has been left by Shahbaz Sharif who retained his Punjab Assembly seat to become chief minister.

NA-5 and NA-13 seats have been vacated by Pervez Khatak and Asad Qaisar of the PTI who retained their provincial assembly seats and were made chief minister and speaker of the KP Assembly, respectively.

JUI-F chief Maulana Fazlur Rehman has decided to quit NA-27 and retain NA24. The Maulana had also won the NA-25 (D.L Khan) seat where by-election has been postponed for a few weeks because of threat of terrorist attacks.

NA-177 has been vacated by Jamshed Ahmad Dasti, NA-235 by Pir Sadruddin Shah Rashdi of the PML-F and NA-216 by Pakhtunkhwa Milli AwamiParty chief Mehmood Khan Achakzai. They had won more than one seat.

NA-83 and NA-254 seats fell vacant after the death of contesting candidates.

By-elections will also be held for 15 seats of the Punjab Assembly, four of the Sindh Assembly, three of the Balochistan Assembly and four of the KP Assembly.

PUNJAB ASSEMBLY: Interior Minister Chaudhry Nisar Ali Khan has vacated his provincial assembly seat (PP-6) and chose to retain his National Assembly seat.

The election in PP-51 could not be held due to death of Mohammad Amjad Rafique. Monis Elahi of the PML-Q gave up his PP-118 seat.

Khawaja Mohammad Asif of the PML-N has decided to quit PP-123 and retain NA seat to become Minister for Water and Power.

PP-161 and PP-247 have been vacated by Shahbaz Sharif and PP-243 by Zulfiqar Ali Khosa.

BALOCHISTAN ASSEMBLY: By-elections will be held in three constituencies PB-29, PB-32 and PB-44.

KP ASSEMBLY: By-elections will be held in four constituencies -KP-23 vacated by former chief minister Amir Haider Khan Hoti, KP-27 by PTI chief Imran Khan, KP-42 by Fareed Khan and KP-70 by another former chief minister Akram Khan Durrani.

SINDH ASSEMBLY: By-elections will be held in PS-12, PS-95, PS-103 and PS-64.