Military leaders and President Obama’s civilian advisers are girding for battle over the size and pace of the planned pullout of U.S. troops from Afghanistan this summer, with the military seeking to limit a reduction in combat forces and the White House pressing for a withdrawal substantial enough to placate a war-weary electorate.

Gen. David H. Petraeus, the top allied commander in Afghanistan, has not presented a recommendation on the withdrawal to his superiors at the Pentagon, but some senior officers and military planning documents have described the July pullout as small to insignificant, prompting deep concern within the White House.

At a meeting of his war cabinet this month, Obama expressed displeasure with such characterizations of the withdrawal, according to three senior officials with direct knowledge of the session. “The president made it clear that he wants a meaningful drawdown to start in July,” said one of the officials, who, like the others, spoke on the condition of anonymity to share internal discussions.

The divergent views about the withdrawal illustrate the unresolved tensions between Obama’s military and civilian advisers over the decision to send more troops to Afghanistan in a last-ditch attempt to salvage a failing war. Although military officials contend that the surge has enabled U.S. forces to blunt the Taliban in key areas over the past several months, White House officials remain skeptical that those gains will survive without the presence of American troops and without U.S. financial aid.

Complicating the debate is growing concern in Washington about the war’s cost, which is estimated to reach $120 billion this year, and polls that show increasing disenchantment, even among Republicans, with a mission that has turned into a complicated nation-building endeavor.

As both sides prepare for what they expect to be a vigorous debate, they are seeking ways to achieve their favored outcome by limiting what the other can do. For the military, that means crafting a narrow set of choices, because there is general agreement that reduction numbers need to originate in the field, not be imposed by the White House. But the National Security Council may attempt to impose its own limitations by setting a date by which all the surge forces must be brought home, the officials said.

Although Obama approved a 30,000-troop increase sought by the military in 2009, he made clear that the surge forces would begin returning home by July 2011. But the pace of that reduction has been in dispute since the president’s surge announcement, with Defense Department officials describing the initial reductions as minor and some of Obama’s other advisers, including Vice President Biden, saying the pullout would be as rapid as the deployment of the surge troops.

Petraeus has said that he will give the president a range of withdrawal options, one of which he will recommend.

Two senior military officials said one set of options being developed by staff officers in Kabul involves three choices: the removal of almost no forces; the withdrawal of a few thousand support personnel, including headquarters staff, engineers and logisticians; and the pullout of a brigade’s worth of troops — about 5,000 personnel— by culling a battalion of Marines in Helmand province that was added after the surge, a contingent of soldiers training Afghan security forces and an Army infantry battalion in either the country’s east or far west.

The officers said Petraeus had not approved the list. They said they expected that a version of the support-personnel withdrawal, perhaps with some combat forces added to the mix, would be the most likely recommendation.

“Our hope is that we’ll be able to get away with no combat troops getting pulled out this summer,” one of the officers said. “But we recognize that may not be possible.”

The Pentagon is hoping to increase its flexibility by dispatching in April an equivalent-size unit to replace a 750-strong Marine battalion that arrived in Helmand in January for a three-month deployment, the officers said. Although those battalions are not part of the 30,000-troop surge, commanders may seek to count their departure as part of the July drawdown.

When he submits the options, Petraeus will outline the risks associated with each, the officers said. The pullout of even one brigade — an option that may be viewed by some civilian advisers as too modest — entails significant costs from the military’s point of view because it could result in the removal of much-needed forces from insecure areas and fewer personnel to train Afghan soldiers.

Military officials contend that recent successes in pushing the Taliban out of parts of Kandahar and Helmand provinces in the south show that the U.S. counterinsurgency strategy is working. They argue that U.S. troops should be kept in place until the Afghan government and its security forces can assume control of those areas.

“We have to make sure we’re focused on an outcome that’s stable and enduring,” said Kimberly Kagan, a part-time adviser to Petraeus and president of the Institute for the Study of War, a Washington-based think tank that supports the surge.

If troops can be freed up in the still-volatile south and southwestern parts of the country, military commanders want those units to be moved to the east, where insurgent violence is escalating. Although the east, which abuts Pakistan’s lawless tribal regions, is no longer deemed the “main effort,” military officials have grown increasingly concerned about the deteriorating security situation there.

But arguments to keep surge forces in Afghanistan for longer than two years contradict promises made by military commanders to Obama during the 2009 White House debate over the troop increase. At the time, commanders insisted that after 18 to 24 months of counterinsurgency operations, they would be able to transfer control of areas to Afghan forces. That timeline led Obama to impose the July 2011 date, which is exactly two years from the arrival of the first wave of additional forces he deployed after assuming the presidency.

“You don’t hear much about 18 to 24 months from the military anymore,” one senior administration official said.

Under one approach being seriously considered by the National Security Council, the White House would seek to impose a date by which all 30,000 surge troops would need to be removed but that would give Petraeus and his successor the flexibility to determine the pace of the withdrawal, two of the civilian officials said.

That would be similar to the approach Obama used to reduce U.S. forces in Iraq, where he declared that the military would have to cut troop levels to 50,000 by August 2010 but left it to Gen. Ray Odierno, then the top commander in Iraq, to set the glide slope of withdrawal.

The Afghanistan date is still under discussion — the final decision would be made by Obama — but one option would be to set it in the fall of 2012, which would be two years from the arrival of the last wave of surge forces. That milestone could appeal to commanders, who could hold on to most of the surge forces through next year’s summer fighting season, but it could provoke opposition from voters and lawmakers who favor a faster drawdown.

In a Washington Post-ABC News poll released in mid-March, nearly two-thirds of Americans surveyed said the war in Afghanistan is no longer worth fighting.

“There are political consequences to having 90,000 troops in Afghanistan through the end of 2012,” the senior administration official said.

For the president’s civilian advisers, a key element of the pullout discussion will be whether U.S. troops are required in as many parts of Afghanistan, and to be as significant a presence, as they are today. Some of the advisers contend that the counterinsurgency mission being conducted is far broader than what was envisaged by Obama when he authorized the surge.

An opening shot in that debate could play out over the next few weeks as the White House considers a request from Petraeus to expand the size of the Afghan army and police force from a total of 305,000 to 378,000.

Military officials contend that the Afghan government needs a larger security service to help stave off the Taliban and assume responsibility from coalition forces. But National Security Council officials have suggested that Afghanistan might not really require such a large army and police force, and that perhaps new village-defense squads could make up some of the difference. The officials also question whether there would be enough U.S. and NATO forces to mentor such a large Afghan force.

The most significant issue is the price tag. Increasing the Afghan security forces to 378,000 could cost as much as $8 billion a year. Much of that would have to be paid for by the United States.

“That’s a huge bill,” the senior official said. “In this fiscal environment, think of what we could do at home with $8 billion.”