Anwar-ul-Haq Kakar, speaks during an interview with AFP in Quetta. AFP
"We first agreed that whoever should be prime minister, he should be from a smaller province so smaller provinces' grievances should be addressed," said Raja Riaz Ahmad after a meeting with outgoing premier Shehbaz Sharif.
Pakistan's parliament was dissolved on Wednesday and by law an election should be held within 90 days, but the results of the latest census released last week means more time will likely be needed to redraw constituencies.
Whenever it happens, it will likely be without former prime minister Imran Khan, who was convicted of graft last weekend and sentenced to three years in jail.
The interim government takes over a country that has been in political turmoil since Khan was dismissed by a no-confidence vote in April last year, and is also facing overlapping economic and security issues.