AP ImagesLawyers in Lahore hold a candlelight vigil.

Editor’s Note: This analysis was updated March 16 to reflect events in Pakistan.

Asif Ali Zardari never aspired publicly to be a political leader in Pakistan — that is until the assassination of his wife, the former prime minister Benazir Bhutto. In his heyday as first spouse he seemed content to use his proximity to power to enrich himself behind the scenes while leading a playboy life. Now it must be clear even to those in Bhutto’s Pakistan Peoples Party who struggled valiantly to support him after he claimed the presidency of Pakistan last year that he has been a colossal disaster–to the nation and the party.

The spectacle on Sunday of an opposition leader whom Zardari tried to silence leading a huge, enthusiastic march against the president toward Pakistan’s capital, barging calmly out of house arrest, through police lines and unafraid of military troops, is only the latest and most telling of testimonies to the president’s misjudgments and blunders. He has almost succeeded in making the rule of General Pervez Musharraf look good.

By early Monday, Zardari capitulated to a major demand by Nawaz Sharif, the opposition leader: former Chief Justice of Pakistan, Iftikhar Chaudhry, who had been sacked by Musharraf, would be returned to the bench. Sharif stopped the march, which the government seemed intent on blocking outside the capital in any case, but the fate of Justice Chaudhry is not Zardari’s only problem.

The long-simmering political confrontation in Pakistan poses multiple problems for the United States. The decision to throw in America’s lot with the Bhutto-Zardari clan in 2007 was made by the Bush administration, another legacy with which the Obama team will need to wrestle. Political chaos is the last environment the US needs as it tries to forge a workable partnership with Pakistan in the face of Islamic pressures, and in advance of an international conference on the future of Afghanistan. What if, in a scenario almost too worrying to contemplate, Zardari were to be forced to step down, or a new parliamentary election called, with an unpredictable outcome? The United States would have to start over cultivating political allies capable of addressing a spectrum of crises.

In recent weeks, with the Pakistan economy in decline after some improvement in the Musharraf years, new pressures from India, Islamic militancy not only on the rise but also able to cobble together no-go zones under Shariah law in previously moderate pockets of the country, broadcast bans imposed and threats of military force, Zardari has thoroughly alienated Sharif’s home base of Punjab, the most prosperous and populous of the country’s four provinces.

Sharif, a wealthy (and allegedly also corrupt) Punjabi from an industrialist family, has been a leading politician in and out of power (and exile) for two decades. He was prime minister twice, leading the Pakistan Muslim League into national election victories before dismissing General Musharraf and being overthrown by him when Sharif attempted to block the general’s plane from landing in Karachi from an official trip to Sri Lanka.

After time in exile in London and the Middle East, Sharif has proved lately to be a very wily and accomplished politician, more fluent in English and more media savvy than when he began his career in the 1980s, and apparently more measured in strategy. That he commands a following in Punjab has never been in doubt, which raises the question of why Zardari, a Sindhi from the south, would launch a frontal attack last month on the elected government of Punjab.

When the Supreme Court ruled in February that Nawaz Sharif would be barred from public office and his brother Shahbaz removed as the chief minister of the province, Zardari’s hand was widely seen behind the judicial decision, which gave the president executive control over the Punjabi provincial government. The gates to dissent were flung wide and mass protests took over streets, parks and highways. Lahore, the center of protest, is not only Punjab’s capital but also Pakistan’s intellectual and cultural center.

By becoming Justice Chaudhry’s champion, Sharif cleverly attracted to his cause some of the same middle-class professionals who marched against Musharraf in 2007 after the dismissal of dozens of judges, including the chief justice. Sharif knew well that Zardari feared that the judge, if reinstated, could revive corruption charges against him that were dropped in a deal between Musharraf and Bhutto to clear the way for her ill-fated return to Pakistan.

Also in the crowds turning out in support of Sharif over the weekend were contingents from at least one Muslim religious party, reporters on the scene noted. In the background of recent developments have lurked fears among Pakistan’s moderate majority that Sharif could enhance his political base by opening more space to Islamic parties, which historically do poorly in national elections. There is also concern that Islamic militants outside the mainstream could take advantage of the political chaos to commit terrorist acts.

As American officials and diplomats worked to cool tempers on both sides, and press Zardari for some concessions, Sharif has gained the upper hand, and is making the most of the moment. On Sunday he accused Zardari of turning the country into a police state, outdoing even Musharraf in trying to stifle protest.

There has also been unrest in the Pakistan Peoples Party and among officials appointed by Zardari. Several have resigned from government. For the party, cursed by refusal of Benazir Bhutto to treat it as anything but a family monopoly without an institutional base, there will have to be some rethinking ahead.