Sharif and Zardari were set to hold a further meeting on Wednesday but Farhatullah Babar, a spokesman for Bhutto's Pakistan People's Party (PPP), would not say if the coalition leaders planned to finalise a decision to impeach Musharraf as reported in local newspapers.
However, Sharif's Pakistan Muslim League-N (PML-N) party said that a decision on impeachment was likely.
"The time to take a final decision has come," said Ahsan Iqbal, a PML-N spokesman after a party meeting in the hill resort of Murree, near Islamabad.
"Pervez Musharraf is trying to harm the democratic process."
The meetings were also said to discuss how to carry out their pledge to reinstate senior judges fired by Musharraf under a state of emergency last November.
Musharraf had been scheduled to leave for China on Wednesday morning, and for a Pakistani leader cancel a visit to the country's closet ally is highly unusual.
But media reports said his decision was prompted by the meetings between Zardari and Sharif.
According to Babar, Zardari had also cancelled a visit to China.
The two parties have been split by the twin issues of what to do about Musharraf and the restoration of the judiciary.
The rift has caused a sense of paralysis in the government and internal coalition squabbling has weakened efforts by the new government to put up a united front against the president.
Musharraf, a long an ally of the US in the so-called war on terror, seized power in a bloodless military coup in 1999 by ousting Sharif's government. But Musharraf's political allies lost February elections, ramping up pressure on him to quit.