According to the New York Times, President Zardari has been severely weakened by his efforts to squelch a national protest and faces defections from the usually cohesive Pakistan Peoples Party (PPP). Sharif, on the other hand, has emerged as a leader in waiting, but with no clear path to power.
Though the way ahead is likely to be messy for everyone, including the United States, and could turn out to be a major distraction from efforts to counter the insurgency, there is hope, American and Pakistani officials point out.
Sharif, who in the past was viewed with suspicion in Washington because of his leaning toward Islamic conservatives, has now been more cooperative, American officials suggest. In Washington, Sharif's relationships with some Islamic parties and with Saudi Arabia are being viewed as useful to the Obama administration.
Sharif has told people that he got along well with the Obama administration's special envoy, Richard C. Holbrooke, during their meeting last month. He speaks admiringly of Secretary of State Hillary Rodham Clinton, whom he met with former President Bill Clinton while in exile in Saudi Arabia.
Pakistani analysts, too, said Sharif could prove to be a useful partner as Washington tried to talk to what it considered reconcilable elements in the Taliban.
"Who from Pakistan can talk to a faction of the Taliban? It's Nawaz," said a senior Pakistani politician who spoke on the condition of anonymity for fear of alienating Sharif.
But Sharif has to play a delicate game because if he is seen as doing Washington's bidding, he will be discredited among much of his constituency, the politician warned.
One encouraging sign for Washington was the role of the army chief, General Ashfaq Parvez Kayani, who let Zardari know that he could not rely on soldiers to confront the protesters threatening to descend on Islamabad.
"The military acted to avert, to correct and to clear the way for full democracy with the center of gravity where it should be - in Parliament and the people," said former army chief and envoy to the United States General (retired) Jehangir Karamat in an article for Spearheadresearch.org, his Web site.
Another positive sign was the nature of the support Sharif garnered after he drove out of his house in a suburb of Lahore on Sunday through barbed-wire barriers, in defiance of a detention order.
Farrukh Saleem, a columnist for The News, said: "He understood the pulse of the country. Those political instincts could serve the Obama administration well if Mr. Sharif continues to work with lawyers and civil society."