An opinion poll on Saturday showed an alliance between the two biggest groups opposed to President Pervez Musharraf was the preferred choice of Pakistan's voters.
Monday's election left none of Pakistan's parties with a majority in the National Assembly and negotiations are continuing between rivals keen to forge a coalition big enough to hold power in the 342-seat parliament.
The fate of Musharraf, who seized power in a military coup in October 1999 and is a key US ally in its war on terror, could depend on what kind of coalition emerges. His supporters, with 39 seats, could still have a say.
Provisional results have been announced for all but 10 seats and the Pakistan Peoples Party (PPP) leads with 87 followed by the Pakistan Muslim League (Nawaz), otherwise known as the PML-N or Nawaz League, with 67.
The Gallup poll suggested an alliance between these two was the preferred choice of supporters. Forty per cent of PPP voters said the PML-N was their second choice and 45 per cent vice versa.
Some 35 per cent of PPP voters and 25 per cent of PML-N voters declined to give a second preference in the poll, held on the day of the election. Gallup did not say how big its sample was.
For much of last year an alliance between the PPP and PML-N seemed unlikely.
The PPP was headed by former prime minister Benazir Bhutto, until she was assassinated on December 27 when leaving a rally, and a deal with Musharraf over her return from years of exile looked likely to extend into a political alliance.
Under that scenario the PML-N party led by Nawaz Sharif, the prime minister deposed and exiled by Musharraf after a coup in 1999, looked likely to be the main opposition bloc.
In the aftermath of Bhutto's assassination and Monday's election, a PPP/PML-N alliance now looks like "the impossible has come to pass", as Dawn newspaper described it in an editorial on Saturday.
If they forge a coalition, it will be the first time in Pakistan's history the two main parties have come together.
In one early sign of cooperation, and one that spells trouble for Musharraf, the PPP and PML-N have agreed in principle to restore judges Musharraf fired when he imposed emergency rule in November.
The judges, if reinstated, can be expected to take up the question of the eligibility of Musharraf to stand for re-election as president while still army chief in October. They had been expected to rule against Musharraf when he imposed the emergency.
On Saturday party elders from across the political divide were meeting separately and with their party faithful to decide the next steps.
The Election Commission is expected to issue official results by March 1, after which Musharraf is expected to convene an inaugural session of the National Assembly.
When that is may depend on whether there is a government-in-waiting because the president has to invite the member commanding the confidence of the majority to become prime minister.