Americans are focused this week on the presidential primaries, but an election campaign halfway around the world will have enormous impact on their lives.

I refer to elections in Pakistan, from which I just returned after a sobering two weeks. Pakistan just deferred its ballot from Jan. 8 to Feb. 18, after the assassination of Benazir Bhutto. Her country has become the key sanctuary for al-Qaeda and Taliban forces, along with other jihadis trying to seize control of portions of a nation that has nukes.

Having visited both Iraq and Pakistan in December, I can say without hesitation that the latter is now the scarier of the two. The Bush administration needs to rethink its Pakistan policy quickly — or watch the threat increase.

The U.S. policy of unqualified support for Pakistani President Pervez Musharraf has got to change.

U.S. officials had been encouraging Musharraf to share power with Bhutto. Musharraf had promised U.S. officials he would rescind constitutional provisions that banned her from a third prime ministerial term. He double-crossed Washington — and her — by failing to do so; instead, he declared martial law in November and threw most of Pakistan's leading judges in jail.

The Pakistani president claimed that martial law was necessary to fight Islamist militants. They have been setting off record numbers of suicide bombs in Pakistani cities and expanding their bases outward from sanctuaries along the Afghan border.

In reality, martial law was meant to let Musharraf hold on to presidential power (Pakistan's Supreme Court had challenged the legitimacy of his reelection by parliament). Indeed, the militants' strength had been multiplying on Musharraf's watch, in part because of his political alliance with Islamist parties who enabled the jihadis. The Pakistani president never made clear to his public the danger that Islamist militants presented.

Only Bhutto had the guts to challenge the widespread belief that the fight against Islamists was America's war, and to proclaim that this fight was necessary for Pakistan's survival.

With Bhutto's death, there is little reason to believe Musharraf will wage the struggle against the Islamists with more vigor. On the contrary, the manner and aftermath of Bhutto's death offer scant hope he will, or can, hold his country together.

If, as looks likely, the delayed elections are blatantly rigged, Pakistan could implode.

Anger had been mounting against the Pakistani leader before Bhutto's death, because of the assault on the judges, and because of perceived corruption in the military. That anger has exploded because government officials provided inadequate security for Bhutto, gave contradictory stories about how she died, and intimidated witnesses. Musharraf blamed "terrorists" for the murder, but many Pakistanis blame the government.

Free and fair elections might offer some prospect of assuaging the country's anger — and leaving the army free to tackle the militants.

But Musharraf can't afford such an outcome.

In a fair vote the two opposition parties together would probably sweep to victory against Musharraf's party — despite the polling delay. If the opposition gained a two-thirds majority, they could boot him from his presidential office. That's why everybody expects that the vote will be fixed.

Even before her death, Bhutto had charged rigging, and planned to submit details to a visiting U.S. congressional delegation, including Pennsylvania's Sen. Arlen Specter. A close Bhutto adviser, Husain Haqqani, outlined for me some of the techniques, including suppression of voter registration, election commissions that refuse to implement the rules, thugs enrolled as election police, and ghost polling places where fraudulent ballots could be cast in bulk.

The White House may be tempted to let Musharraf retain power — no matter how illicit — on the grounds that only he can preserve stability and fight against militancy.

Yet that scenario died with Bhutto. Musharraf's credibility is shot, and blatant poll-rigging guarantees continuing instability. This is why the United States, in concert with other nations, should exert every pressure on Musharraf to ensure elections are fair. Best would be a caretaker government of national consensus and new election commissions.

Minimally, the White House must insist on full rights for international election observers. A push for an international investigation into Bhutto's death (beyond the assistance of Scotland Yard) would also be wise.

This is not a question of American interference into Pakistan's internal affairs. Pakistani elections will shape the effort to stabilize a nuclear-armed country where terrorists are deepening their hold. They are the world's concern and yours — as crucial to our future as Iowa caucuses and New Hampshire polls.

The U.S. policy of unqualified support for Pakistani President Pervez Musharraf has got to change.

Trudy Rubin is a columnist and editorial-board member for the Philadelphia Inquirer. Reach her at trubin@phillynews.com.