Asif Ali Zardari, the Pakistani politician considered a front runner to become the country's next president, remains under criminal investigation in Switzerland over allegations that he received kickbacks from two Swiss-based companies while his wife, the late Benazir Bhutto, served as the country's prime minister in the 1990s, a Swiss judge and two Swiss lawyers close to the case told NEWSWEEK.

But Zardari, who has always claimed that corruption allegations against him were politically motivated, may be using his growing political clout in Islamabad to pressure Swiss authorities to curtail, or even close, their long-running investigation into his affairs, say Swiss legal sources, who requested anonymity discussing sensitive matters.

Zadari, through a spokeswoman, maintains that the probe is already closed. "Mr. Zardari feels that you have been misinformed and that the case that you are referring to is closed," wrote Farah Ispahani, in response to an e-mail from NEWSWEEK. "Please be careful about reporting something that may have been planted."

Zardari, who co-chairs Bhutto's political movement and was one of her closest advisers when she headed Pakistan's government, has emerged as perhaps the most powerful figure in Pakistani politics following the resignation this week of President Pervez Musharraf. U.S. officials say they already view Zardari as one of most important Pakistani officials the U.S. deals with on sensitive issues such as the hunt for Al Qaeda and Taliban leaders in volatile tribal areas along the country's border with Afghanistan.

But U.S. officials remain wary of Zardari because of corruption allegations that have swirled around him for years. In the 1990s, when Bhutto served two terms as prime minister and her spouse served a stint as investment minister, Zardari earned the nickname of "Mr. Ten Percent" because of allegations that he had received kickbacks on state contracts. He spent more than eight years in jail in Pakistan during corruption investigations, though he was never convicted of any crime.

Zardari, Bhutto and their supporters have always maintained that the corruption allegations against the couple were trumped up by powerful political enemies, including both Musharraf and Nawaz Sharif, a former prime minister who is now Zardari's principal rival for power. Lawyers for Bhutto and Zardari say they always maintained their innocence of any corruption or other criminal accusations. "For most Pakistanis this is a matter that is now closed," said a senior Pakistani government official who spoke on condition of anonymity. "The primary motivation [behind the investigations] was political."

The Swiss investigations were opened years ago, during Sharif's tenure as prime minister. His government requested official legal assistance from Switzerland, where Pakistani authorities suspected that the couple had stashed proceeds from alleged corrupt activities. The Pakistani government hired its own lawyers in Switzerland to gather evidence against Bhutto and Zardari and help Swiss investigators with their inquiries.

In 2003, these investigations resulted in a series of court orders against Bhutto, Zardari and one of their Swiss lawyers, Jens Schlegelmilch. The orders, akin to misdemeanor guilty findings by a U.S. justice of the peace, were issued by Judge Daniel Devaud, an investigating magistrate in Geneva who has handled many high-profile investigations into the alleged laundering of corrupt payments through Switzerland by foreign politicians.