Stephen J. Hadley was national security adviser in the George W. Bush administration.

U.S. officials are struggling again with Afghan President Hamid Karzai. After painful and prolonged negotiations, they concluded a draft bilateral security agreement last year that lays the foundation for leaving U.S. military forces in Afghanistan after 2014. It is expected to involve 8,000 to 10,000 U.S. troops with counterterrorism, training and other responsibilities in support of Afghan forces.

Most U.S. experts on Afghanistan believe that such a residual force is critical if Afghan forces are to continue to professionalize. Only with such help will they have a reasonable chance of containing the Taliban and giving Afghan authorities the space to negotiate a political settlement that includes the Taliban. Some NATO forces would remain, but only if U.S. troops stay.

Most experts believe that without residual forces the billions of dollars in financial support promised for Afghan security forces and for Afghanistan’s economic development will not materialize. Few believe that any Afghan government would survive long without this assistance. So the stakes are high — for Afghanistan and for preserving the investment of lives and treasure that the United States and its coalition allies have made over the past 12 years.

Initially Karzai said he would sign the agreement after a loya jirga, a traditional congregation of Afghan leaders, approved the pact. The loya jirga approved the deal in November, but Karzai demanded further concessions: an end to counterterrorism raids into Afghan homes at night, active U.S. support for the peace process with the Taliban and non-interference in the April presidential election that will determine Karzai’s successor. Lately, he has threatened to leave the matter to his successor.

U.S. officials have responded by pressuring Karzai directly and indirectly. They have set a succession of deadlines and said the agreement must be signed in “weeks, not months.” So far, nothing has worked.

U.S. officials need an alternative approach.

One option would be for President Obama to make a public statement praising Afghanistan’s progress in assuming responsibility for its security; improving the education, health and well-being of its citizens; and preparing for the April election. To support that progress, Obama would say, he has directed U.S. forces to curtail all but essential night raids. He is committed to facilitating the peace process, he would note, and will pledge full support for an election free from all outside influences.

These statements would not represent a major U.S. policy change, but together they would offer Karzai a face-saver if he wishes to sign the security agreement.

Next, Obama could announce the number of troops that he is prepared to leave in Afghanistan post-2014 and direct the Pentagon to develop plans on that basis. He would call on our NATO allies to announce similar force commitments.

This step would go a long way toward reassuring Afghan presidential candidates, and the Afghan people, of the United States’ post-2014 presence. The lack of such reassurance has become a source of serious instability, threatening the election and the morale of Afghan security forces. For similar reasons, Obama should resist any pressure to set a date for the termination of the post-2014 U.S. deployment.

Third, Obama could state that while he is willing to sign the bilateral security agreement with Karzai, he also is willing to sign it with the next Afghan president. U.S. officials should stop pressuring Karzai — or anyone else — for a signature before the April election. Such pressure only strengthens Karzai’s hand, encourages further delay and makes the United States look desperate.

Obama should make clear that his commitment of troops is dependent on the bilateral security agreement being signed. But a signing by a new Afghan president would give more than enough time to complete the necessary U.S. military planning before year’s end. Indeed, experts say that even without the deal, U.S. forces could remain in Afghanistan after 2014 under the existing status-of-forces agreement, though our allies would have to negotiate new agreements for their forces with the new Afghan government.

Washington Post-ABC News polling last month suggested that more than 60 percent of Americans believe the Afghan war was not worth fighting. But the same poll also found that 55 percent support leaving some U.S. forces for training and “anti-insurgency” operations. And lawmakers’ public statements suggest that a post-2014 deployment would have bipartisan support in Congress.

Obama should avoid any suggestion that he might embrace a “zero option” and leave no U.S. troops in Afghanistan after 2014. Almost every Afghan expert believes that would destabilize Afghanistan, threaten the outcome of the election and risk the collapse of Afghan security forces. This would profoundly affect U.S. security interests. Afghanistan again would become a haven for terrorists — who, history shows, would attack U.S. interests and territory. Afghanistan would contribute to destabilizing a nuclear-armed Pakistan. And the Afghan people would forfeit the progress they have made, with our help, in building a more tolerant, inclusive, secure and prosperous society.

Afghanistan’s presidential election is less than three months away. U.S. policy must not be based on frustration with Karzai’s mercurial behavior but on ensuring the election of a legitimate successor to Karzai with whom the United States can sign a security agreement that is overwhelmingly in the interests of both countries.