Under the broad outlines of the proposed power-sharing pact, Musharraf would relinquish his military post, and corruption charges against Bhutto would be dropped. In addition, Bhutto, who has already served two terms as prime minister, would get special parliamentary approval to serve a third.
But the deal-making, so common in Pakistani politics, has faced unaccustomed scrutiny from critics, including the previously quiescent Pakistani media.
"How is the Musharraf- Benazir deal going to serve the national interest?" the Urdu daily Nawa-i-Waqt asked last week. "How will it pave the way for real democracy in the country?"
Bhutto, who has said she will announce her own plans for a return to Pakistan this week, is not the only one whose political fortunes have been greatly complicated by Sharif's resurgence.
What remains of Musharraf's core constituency is being eroded by the Sharif juggernaut. Last week, a lawmaker with the ruling party, Akhtar Kanju, defected to Sharif's side, saying he would not support Musharraf seeking another term as president while still head of the army.
Sharif's lieutenants have issued defiant statements.
"We warn the rulers that the small hurdles they are trying to create, the people of Pakistan will trample all these hurdles under their feet," said the party's acting leader and senior politician, Javed Hashmi, who was freed from prison by the Supreme Court last month while it reviews his case.
Bhutto's supporters accuse Sharif of trying to provoke a confrontation with the government.
"He wants to take it to the streets, and then we'll have chaos and bloodshed," said a senior Bhutto aide in London, Wajid Shamsul Hassan. "And then there will be a pretext for imposing martial law. That's what we fear."
The option of imprisoning Sharif, thus making him appear a martyr to his cause, carries too many risks for Musharraf, said the English-language Dawn newspaper.
"The government has clearly exhausted all options of trying to keep Mr. Sharif out, and should now accept his decision to return . . . with dignity and grace," it editorialized last week.
Some observers doubt that Sharif has real political staying power of his own, saying that the support for his return probably is simply another way of expressing disdain for Musharraf.
"At the moment, this is not so much a pro-Sharif movement as an anti-Musharraf one," said retired Brig. Gen. Naeem Salik, now at Johns Hopkins University. "We can't know yet whether it will be anything more than that."