Pakistani lawmakers on Saturday voted in the presidential poll expected to be swept by the ruling Pakistan People's Party chief Asif Ali Zardari.

Fifty-two-year-old Zardari is engaged in a three-corner fight with Pakistan Muslim League-Nawaz candidate Saeed-uz-Zaman Siddiqui and opposition PML-Q leader Mushahid Hussain Sayed.

He is expected to win easily despite the PML-N's decision last month to pull out of the ruling coalition as the PPP co-chairman has the backing of several smaller parties and independent lawmakers.

Chief Election Commission Qazi Muhammad Farooq supervised the polling in a joint sitting of the 100-member Senate and the 342-strong National Assembly, the two houses of Parliament.

The voting, which will last till 3 pm local time, was being held simultaneously in the four provincial assemblies of Punjab, Sindh, North West Frontier Province and Balochistan.

The Election Commission is expected to announce the unofficial result shortly after the end of the polling, which was being conducted through secret ballot.

The election was necessitated by the resignation last month of former president Pervez Musharraf [Images], who stepped down to avoid impeachment by the ruling coalition.

A week after his resignation, the PML-N pulled out of the alliance accusing Zardari of reneging on promises to restore judges deposed during last year's emergency and to field a non-partisan candidate for the presidential poll.

Musharraf had swept the last presidential election held in October 2007 to obtain a second five-year term, but the PPP and PML-N had opposed his re-election, saying the electoral college had comprised the national and provincial assemblies that were on the verge of completing their terms.