he U.S. military has revised plans to withdraw troops from Afghanistan to allow the White House to wait until President Hamid Karzai leaves office before completing a security pact and settling on a post-2014 U.S. troop presence, officials said.

The option for waiting reflects a growing belief in Washington that there is little chance of repairing relations with Mr. Karzai and getting him to sign the bilateral security agreement before elections scheduled for the spring.

"If he's not going to be part of the solution, we have to have a way to get past him," said a senior U.S. official. "It's a pragmatic recognition that clearly Karzai may not sign the BSA and that he doesn't represent the voice of the Afghan people."

The military plan is the most significant example to date of how the U.S. has sought to minimize its reliance on Mr. Karzai, whose refusal to sign the security agreement amid a flurry of anti-American statements has upset Washington policy makers. The White House has said Mr. Karzai's refusal has raised prospects that President Barack Obama will order a complete U.S. troop withdrawal this year. Afghan officials had no immediate comment.

Mr. Obama and Defense Secretary Chuck Hagel have signaled their displeasure with Mr. Karzai by limiting their contacts with him. The U.S. and Afghan leaders haven't held a videoconference call to discuss the war effort since the summer, officials said. Mr. Hagel visited Afghanistan in December but didn't meet Mr. Karzai. Susan Rice, Mr. Obama's national security adviser, had a frosty meeting with Mr. Karzai in Kabul in November.

The new message from the U.S. military amounts to an about-face from what some Pentagon leaders had been saying publicly for months.

In November, Mr. Hagel said that "we need to have that agreement signed by the end of the year," and added: "I think President Obama has been very clear on that, that he can't make any commitments or define any future role and troop numbers post 2014 until we have that."

Likewise, White House Press Secretary Jay Carney has said repeatedly in recent weeks that the U.S. wants the Afghanistan government to sign the security agreement in matter of "weeks."

Now U.S. military leaders say a further delay is less of a concern, from their perspective. "The real challenge for the BSA delay is not associated with military planning," one senior U.S. military official said.

Senior U.S. military and administration officials said the U.S. still feels a sense of urgency to get the security pact signed because of the implications for North Atlantic Treaty Organization partners who need more time to plan deployments. "The costs go up. The complications go up," one senior military official said.

To step up the pressure, officials said, Mr. Obama is expected to ask the military to initiate planning for a full troop withdrawal from Afghanistan if Mr. Karzai doesn't sign the security pact soon, most likely before a NATO summit in Brussels this month.

By scaling the drawdown to accommodate additional delays, U.S. military leaders wanted to make sure logistical hurdles wouldn't be the deciding factor for Mr. Obama if he decides to withdraw all U.S. troops from Afghanistan.

The revised drawdown schedule is based on a new plan the Pentagon presented to the White House in January that calls for keeping 10,000 U.S. troops in Afghanistan after 2014 at a limited number of bases. Military commanders say the force is needed to provide a stabilizing presence after this year's election. Military officials also believe a limited advisory mission will help maintain progress Afghan security forces made in recent years.

The Obama administration has been skeptical of the value of a long-term troop presence. The new military plan would draw down that 10,000-member force in two years, with the intent of being able to remove all American troops by the end of the Obama administration except for military personnel who would work in a defense office at the U.S. Embassy in Kabul.

Mr. Karzai, in refusing to sign the security pact, has said his successor should make the decision. The Afghan president has been playing what U.S. officials described as a "game of chicken" with the White House. "We're just pulling our car off the side of the road," a senior U.S. official said.

But even with additional time, officials said uncertainties remain. Voting is scheduled for April 5, but with no single candidate poised to get more than 50% of the vote, a second round looks likely. This means a new government is unlikely to take office before August.

Senior U.S. officials said the military's revised drawdown plan would allow the U.S. to wait until the end of summer, if not a bit longer, to begin a final pullout, if one is ordered.

Most of the main candidates have said they are in favor of a U.S. military presence in Afghanistan after 2014. Privately, so do some of Mr. Karzai's senior advisers. But many presidential contenders have become reluctant to openly back the BSA, say Afghan and Western officials, for fear this would alienate Mr. Karzai just as election campaigning gains steam.

Under the revised drawdown plan Gen. Joseph Dunford, the commander of U.S. and NATO forces in Afghanistan, put together in recent weeks, the U.S. military will have all equipment in place in Afghanistan by July to support a post-2014 force that includes 10,000 American troops, officials said.

The equipment is likely to include helicopters and limited numbers of mine-resistant troop transport vehicles. It would mainly be used to protect bases in the country that would be used for training and advising Afghan command units, and to house American spies and diplomats.

That means the Pentagon will go into the summer prepared to accommodate either outcome: a presidential decision to keep 10,000 troops in Afghanistan post-2014 or an order to pull all of the troops out by year-end, officials said.

The adjustments have the backing of Gen. Martin Dempsey, the chairman of the Joint Chiefs of Staff. A senior military official said Gen. Dempsey's goal was to provide "more decision space to policy makers."

The biggest challenge for the U.S. military would be closing big air bases like the one in Kandahar in southern Afghanistan. In the past, military officials estimated that it could take as long as 10 months to close such bases. But commanders now say they can do the job in less time.

While the U.S. military now believes it can wait until the summer—or longer—to decide on a post-2014 presence, other NATO allies have told the Pentagon that they are more concerned about further delays in getting a security agreement.

Unlike the U.S., these countries don't have the equipment and military capabilities needed to wait until the fall to make a final decision.

Rear Adm. John Kirby, the Pentagon's press secretary, said there has been no change in the Pentagon's position that the security accord should be signed "as soon as possible," adding, "Otherwise we are going to have to start planning for a complete withdrawal."

But a senior U.S. official said the goal is to provide the White House with the flexibility to wait out Mr. Karzai's term if he refuses to sign the agreement.

"Our job is to be able to provide options," the official said. "This maintains flexibility should Karzai take a pass on the BSA. But that is not the desired outcome."