ISLAMABAD, Pakistan -- Pakistan's ruling coalition teetered on the brink of collapse Saturday as the two main partners argued over a successor to ousted President Pervez Musharraf.
Former Prime Minster Nawaz Sharif, who heads the junior partner in the coalition, demanded the dominant Pakistan People's Party slash the president's powers before he would support its candidate.
Asif Ali Zardari, head of the PPP and widower of the party's assassinated leader Benazir Bhutto, agreed Saturday to run for the presidency.
Sharif also pushed forward the deadline for restoration of dozens of judges sacked by Musharraf -- another key issue dividing the two main parties since they forced the president from power less than a week ago.
Still, pressure was building for the two sides to end differences that appeared increasingly irreconcilable.
Presidential elections by parliament were set for Sept. 6 and the political infighting is a distraction from militant violence flaring in the volatile northwest, where 37 insurgents were killed Saturday in retaliation for a string of deadly suicide bombings.
Though Zardari is a longtime Musharraf critic, he would likely continue the former general's support for the U.S.-led war against terrorism.
But Zardari's climb to power would dismay many in this nation of 160 million who view him as a symbol of corruption that tainted its last experiment with civilian rule in the 1990s.
He won the nickname "Mr. 10 Percent" for alleged graft during his wife's turns as prime minister.
Despite the backing of the PPP, his election is far from certain.
Sharif, who heads the second-largest party in parliament, was one of Bhutto's bitter rivals and has been threatening to bolt in a struggle over power.
He demanded after meeting with Zardiri's lieutenants Saturday that the PPP agree to sharply reduce the powers of the new president before he'd support their candidate.
Sharif wants the head of state to be deprived of the constitutional right to dissolve parliament or to appoint chiefs of the armed forces -- but Zardari's name was thrown into the race without any such guarantee.
Sharif, ousted by Musharraf during his 1999 coup, also pushed up a middle-of-the week deadline for the restoration of judges fired by Musharraf late last year to avoid challenges to the former strongman's rule.
He wants an agreement by Monday that all -- including former chief justice Iftikhar Mohammed Chaudhry -- will be back on the bench, saying a surprise Sept. 6 presidential election date forced him to push up his deadline.
Zardari, though he wants the judges reinstated, is not quite as enthusiastic. Like Musharraf, he has accused Chaudhry of being too political, and says it should be up to parliament to decide.
Analysts say he also might fear that the former chief justice would revive corruption cases killed off by Musharraf as part of a failed effort to form a pro-Western power-sharing deal with Bhutto before her assassination.
The PPP, fearing the loss of its coalition partner, has already started seeking support from other smaller parties.
The crisis comes as Pakistan is increasingly threatened by extremist violence.
The ruling coalition -- united primarily in their hatred of Musharraf -- dabbled in peace talks with the militants soon after taking power five months ago, something the former president briefly tried as well.
But after limited success, they have increasingly relied on military force to try to beat back al-Qaida and Taliban-linked insurgents in the remote and rugged tribal regions along the border with Afghanistan.
The militants have responded with force in recent days.
The Taliban claimed responsibility for one of the country's deadliest-ever terrorist attacks, a twin suicide bombing at a massive government weapons complex that killed 67 people and injured more than 100 on Thursday.
On Saturday, a car packed with explosives rammed into a police station in Swat, a former tourist destination, killing six officers and injuring several, said local police official Mohib Ullahn.
A roadside bomb in the nearby village of Bari Kot killed one civilian and injured four, said Muslim Khan, a spokesman for the Taliban militants, threatening more violence unless the army stops operations against them.
Associated Press writers Munir Ahmad in Islamabad, Babar Dogar in Lahore and Anwarullah Khan in Bajur contributed to this report.