Military ruler Pervez Musharraf's term as president officially ends today at the same time as parliament dissolved.
Mr Musharraf appointed the chairman of the upper house Senate as caretaker prime minister to oversee general.
As expected, Senate chairman and ruling party member Mohammadmian Soomro will head a caretaker line-up that will be sworn in on Friday.
The government said Mr Musharraf, as the incumbent, would remain in office as both army chief and president until the Supreme Court rules on the legality of his victory in the presidential election on 6 October.
Opposition leaders including detained former premier Benazir Bhutto have called on Mr Musharraf to quit.
Mr Musharraf's lawyers told the Supreme Court in September that his five-year term in office would end on 15 November.
He also vowed to shed his uniform before his second term.
The national parliament meanwhile is set to dissolve at midnight after serving the first full term in the history of Pakistan, paving the way for a caretaker government ahead of elections Mr Musharraf has promised by 9 January.
The interim government will be sworn in Friday.
The remaining provincial assemblies are to be dissolved around 20 November.
The opposition, most of whom are either detained, exiled or under house arrest, are considering whether to boycott of the polls, saying they can be neither free nor fair under the state of emergency.
Meanwhile, authorities begun allowing private television news channels back on the air nearly two weeks after they were banished under a state of emergency imposed by President Musharraf.
Two of four main national news channels that disappeared from cable services after the 3 November emergency were back on air today. International channels CNN and the BBC were still blocked but Sky News reappeared a day after it too went off the air.
