LAHORE, Pakistan (Reuters) - Interim Pakistani leader Shahid Khaqan Abbasi took control of prime ministerial duties on Thursday after a guard of honor amid growing uncertainty that the brother of ousted leader Nawaz Sharif will eventually take over the job as planned.

Pakistan's Prime Minister Shahid Khaqan Abbasi reviews the honour guard in Islamabad, Pakistan August 3, 2017. REUTERS/Caren Firouz

Sharif, disqualified by the Supreme Court last week, named Abbasi as temporary prime minister and outlined plans for brother Shahbaz Sharif to take over once he contests and wins a parliamentary by-election in less than two months.

But doubts seem to have surfaced about those plans since Sharif’s ruling Pakistan Muslim League-Nawaz (PML-N) party used its hefty majority in the National Assembly to elect Abbasi as prime minister on Tuesday.

Three senior PML-N officials told Reuters that Shahbaz’s eventual installation as prime minister was no longer a foregone conclusion, while two of Shahbaz’s Lahore-based aides added that the chances of him taking over were receding.

“Nawaz Sharif is in two minds about Shahbaz’s premiership,” said one of Shahbaz’s aides in Lahore.

Asif Khawaja, former defense minister and staunch Nawaz ally, told Geo TV late on Wednesday that the plan to make Shahbaz premier was “almost confirmed”, but added Nawaz as the leader of the party “has the prerogative to revise (or) amend his decision - or stick to it”.

Opposition politicians have slammed Nawaz’s plans as dynastic, with opposition party leader Imran Khan decrying Pakistani politics as a “form of monarchy”.

Still, analysts say the relatively smooth transition to Abbasi after Nawaz was disqualified has eased fears that nuclear-armed Pakistan could be plunged into a prolonged bout of political turmoil.

Former petroleum minister Abbasi has frequently traveled to the Sharif family home in Murree, in the hills northeast of Islamabad, and has spoken openly about “consultations” with his old boss, bolstering the widespread view that the toppled leader is the power behind the throne.

Nawaz resigned on Friday after the Supreme Court disqualified him for not declaring a small source of income - something he rejects receiving.

He has criticized the judiciary for cutting short his third stint in power and his allies have hinted that elements of the powerful army may have played a role, but the veteran leader retrains widespread backing of his party.

2018 POLL

PML-N officials say the main reason why Shahbaz may not take over is linked to the 2018 general elections, and the party’s fears that its grip on the vital Punjab province will weaken if he steps down as chief minister.

The way Pakistan’s political system is set up means any party that sweeps Punjab, which houses more than half of Pakistan’s 190 million people, will most likely go on to form a government after the general elections in mid-2018.

Shahbaz has served as chief of Punjab since 2008, delivering big wins for PML-N and forging a reputation as a competent administrator whose workaholic habits have contributed to timely completion of infrastructure mega projects popular with voters.

“The safer choice is to leave Shahbaz in Punjab,” said a senior PML-N official. “Most people think that it would be safer and better at this stage to not disturb these things too much.”

Abbasi and Sharif are due to hold further discussions about the formation of the new cabinet and PML-N officials expect a decision to be made about Shahbaz’s future in a day or two.

Abbasi, a Western-educated businessman who founded a budget airline, is regarded as an absolute Nawaz loyalist.

Abbasi spent most of his political career by Nawaz’s side and the two were jailed after the 1999 coup by General Pervez Musharraf.