Attacks targeting Pakistan's landmark elections killed 10 people on the eve of the vote as the Taliban stepped up threats Friday, warning voters to boycott polling stations to save their lives.
Polls open at 8:00 am (0300 GMT) and close at 5:00 pm, allowing an electorate of more than 86 million to vote for the 342-member national assembly and four provincial assemblies in Khyber Pakhtunkhwa, Punjab, Sindh and Baluchistan.
Saturday's vote marks the first time that an elected civilian administration has completed a full term and handed power to another through the ballot box in a country where there have been three military coups and four military rulers.
The front-runner is ex-prime minister Nawaz Sharif, head of the centre-right Pakistan Muslim League-N (PML-N) but the campaign has been electrified by former cricket star Imran Khan with promises of reform and an end to corruption.
Pakistan's umbrella Tehreek-e-Taliban (TTP) movement says democracy is un-Islamic and has singled out the outgoing parties for particular threat, curtailing campaigning for the Pakistan People's Party (PPP) and its main allies.
Attacks on politicians and parties have killed 127 people since mid-April, according to an AFP tally, and the Human Rights Commission of Pakistan (HRCP) said the elections were the most violent in the country's history.
"To revolt against this system, the TTP have planned several actions on May 11, so we appeal to the people to stay away from polling stations to save their lives," Taliban spokesman Ehsanullah Ehsan said.
A candidate for the provincial assembly in Sindh was shot dead along with two supporters in the financial capital Karachi on Friday, officials said.
Shakil Ahmed was a businessman and an independent candidate for the assembly in the southern province but was supported by a faction of the Muttahida Qaumi Movement (MQM), the main party which controls Karachi.
"We have received three dead bodies, including that of Shakil Ahmed," said Doctor Semi Jamali, head of the emergency department at Jinnah Hospital.
Khalid Hamid, spokesman for the MQM faction, said he was shot with two supporters in the Landhi area where they went for an election meeting.
Gunmen attacked an armed convoy carrying ballot papers in Mastung district, south of Quetta, the capital of Baluchistan province.
"They first fired rockets and then used guns and other small weapons. Two security personnel members have died and five others are injured," Baluchistan home secretary Akbar Hussain Durrani told AFP.
In the northwest, a motorbike bomb killed four people and wounded 15 close to offices of different parties in the main town of North Waziristan, the premier stronghold of Taliban and Al-Qaeda-linked groups on the Afghan border.
Security officials said PML-N, Khan's Pakistan Tehreek-e-Insaf (PTI) and right-wing religious party Jamiat Ulema-e-Islam, an ally of the outgoing government, had offices nearby.
A bomb near an office of the secular Awami National Party (ANP) in the northwestern district of Swabi killed one person and injured three others, police said.
There were no claims of responsibility for any of Friday's attacks.
A spokesman confirmed that President Asif Ali Zardari had voted by post in the election after the Taliban directly threatened his PPP party.
Zardari's wife, former prime minister Benazir Bhutto, was assassinated in a gun and suicide attack in 2007 before the last election and her successor as PPP chairman, their son Bilawal Bhutto Zardari, is too young to run.
It is unclear whether Bilawal will even vote. Party officials have said the threats against him are too serious for him to appear in public.
Presidency spokesman Farhatullah Babar confirmed to AFP that Bilawal had been denied permission for a postal ballot but did not give an explanation.
The HRCP has voiced "acute concern" not just over threats and violence targeting individuals "but much more from the manner in which the violence has already impaired the fairness of the elections almost beyond repair".
Most commentators expect Sharif's centre-right Pakistan Muslim League-N to win but it remains unclear to what extent Pakistan Tehreek-e-Insaf can provide an upset and restrict his chances of forming a stable coalition.
More than 600,000 security personnel, including tens of thousands of soldiers, have been ordered to deploy to guard against attacks on polling day.