Pakistan will elect a new ceremonial head of state on Tuesday, replacing Asif Ali Zardari with a successor set to cement Prime Minister Nawaz Sharif's hold on power.

Boycotted by the opposition Pakistan People's Party, which complained it was not consulted on bringing the election forward from Aug 6, Sharif's candidate is certain to win.

Mamnoon Hussain is a businessman, close ally of the premier, a long-serving member of the main ruling Pakistan Muslim League-N and comes from the southern province of Sindh.

His loyalty to Sharif and his low profile will shore up the prime minister's authority and provide a stark contrast to Zardari, considered a sharp political operator behind the scenes.

Pakistan faces enormous challenges. A debilitating power crisis needs to be solved, Taliban violence remains unchecked and US relations are complicated by drone attacks targeting militants.

Supporters say Hussain's election could be important domestically by giving the south some stake in the federal administration, otherwise dominated by Punjab, Sharif's power base.

The Pakistan People's Party withdrew its candidate Raza Rabbani after the Supreme Court accepted a Pakistan Muslim League-N request to change the date as lawmakers would be busy with pilgrimage and prayer at the end of Ramadan.

Rabbani, a highly respected senator capable of commanding cross-party support, said the new date would not leave enough time for campaigning in the four provincial capitals and in Islamabad.

Pakistani presidents are elected by the members of four provincial assemblies, and both houses of parliament.

There are two candidates: Hussain and respected, retired Supreme Court judge Wajihuddin Ahmed, nominated by the third largest party of cricket hero Imran Khan.

Zafar Iqbal Jhagra, a covering candidate for the Pakistan Muslim League-N, withdrew his nomination papers on Saturday.

"There was no reason for Jhagra to be in the race when Hussain's nomination papers have been accepted," party spokesman Asim Khan said.

Voting will begin at 10 am and last until 3 pm, with the result expected to be announced late on Tuesday.

Constitutional amendments passed by the last Pakistan People's Party government mean that the presidency is again a ceremonial post, a status likely to be cemented by the fact that Hussain has little personal clout.

Sharif won a commanding general election victory in May, which marked the first time a Pakistani civilian government completed a full term in office and handed authority over to another at the ballot box.

After formally stepping down in September, many expect Zardari to spend significant time abroad out of concerns for his security and to escape the possibility of legal action for alleged corruption.

Zardari was unpopular and divisive within the Pakistan People's Party, and his departure will open a new chapter in the center-left party, which ran a rudderless general election campaign earlier this year.