WASHINGTON - Growing numbers of Americans dying in battle for a deeply corrupt government. Radical Islamic terrorists. A billion-dollar narcotics trade. Custody of nuclear weapons at risk. Osama bin Laden.
The worsening war prompted a pointed exchange between Sarah Palin and Joe Biden last week, with the vice presidential candidates disagreeing on whether an Iraq-style troop "surge" could yield results in Afghanistan.
The dispute, and a related one earlier between McCain and Obama, underscore how the war against Taliban and other insurgents in Afghanistan, and the Islamist insurgency that the war has spawned inside Pakistan, are likely to be the most urgent and most difficult national security problem to confront the candidate who takes office Jan. 20.
Until now, the Bush administration has insisted that the United States had time to end the Iraq war before turning its full attention to Afghanistan. But analysts say it's harder to make that case.
Despite seven years of U.S. military involvement, Afghanistan is being "gradually lost," said Michael O'Hanlon of the Brookings Institution, an assessment shared by many civilian and military experts.
There are few easy strategic or tactical choices. A shortage of U.S. and allied combat troops has forced a growing reliance on air power, senior military officers say.
Heavier airstrikes have increased civilian casualties, raising local hostility and tacit support for the insurgents, commanders acknowledge.
"We are in a very tough counterinsurgency fight and will be for some time" is how Gen. David McKiernan, the top U.S. commander in Afghanistan, put it last week.
"I won't say things are all on the right track," he told reporters at the Pentagon. "It might get worse before it gets better."
For the most part, the two presidential camps have passed quickly over Afghanistan by promising to send more troops.
But the Pentagon says it doesn't have the troops to send without a reduction of forces in Iraq.
Both McCain and Obama say they will withdraw troops from Iraq if conditions allow. But the senior U.S. regional commander, Gen. David Petraeus, has said conditions in Iraq are too "fragile" to permit a further reduction now.
The McCain and Obama camps also have endorsed increasing Afghan security forces and non-military U.S. aid.
But they've had difficulty trying to detail a specific strategy for Afghanistan.
Both McCain and Palin insist that an Iraq-style "surge" strategy could be transferred to Afghanistan. In the Thursday debate, Palin said the strategy of "clearing, holding, rebuilding, the civil society and the infrastructure ..." would be "a difference with the Bush administration."
What she described, though, is a very general approach to counterinsurgency warfare that was tried in Iraq for several years before the "surge" troops began arriving in the spring of 2007.
But factors that made the surge a success in Iraq - including using troops to provide neighborhood safety that sped the pace of political reconciliation - are missing from Afghanistan.
Seventy percent of the population is scattered across rural areas, making it impractical to defend population clusters. The government is hobbled by corruption and a severe shortage of educated people, problems more difficult to resolve than sectarian divides.
"Afghanistan is not Iraq," McKiernan told a small group of reporters a day before the Biden-Palin debate. For that reason, he said, "I don't use the word surge" as a strategy for Afghanistan.
McKiernan has asked for four additional brigade combat teams for Afghanistan, about 16,000 troops. But winning the war "is not about more boots on the ground," he said. "Ultimately, this will require a political outcome."
That approach is central to Obama's thinking as well, said Richard Danzig, Navy secretary under President Bill Clinton and Obama's top national security adviser. "There are opportunities to use capabilities besides military power in Afghanistan that have been underutilized in administration policy," he told defense reporters last week.
The McCain-Palin campaign did not respond to requests for an interview with a senior national security adviser.
Up to now, even good ideas have gone unfulfilled for lack of money or willpower.
"Within the Afghan expert community there hasn't been disagreement over what needs to be done - the problem has been implementation," said Alexander Thier, an Afghanistan expert at the U.S. Institute of Peace who has served as a United Nations officer in Afghanistan.
For example, it has long been a U.S. goal to expand the size of the Afghan army and police - now a key demand of both McCain and Obama.
But the Pentagon reported this summer that it has been able to deploy fewer than half the trainers needed for the Afghan army and 39 percent of the police trainers required.
Last spring it deployed a Marine battalion to Afghanistan to train police, but the unit spent much of its time fighting insurgents.
The fighting has gotten so intense, McKiernan said last week, that he is seeking replacement battalions that will spend only half their time as trainers and the remainder in combat.
Money has been a problem as well.
In Thursday's debate, Biden claimed that the U.S. has spent "more money in three weeks on combat in Iraq" than in seven years "building" Afghanistan.
His numbers were off, though. According to the Congressional Research Service, combat operations in Iraq in fiscal 2008 cost $2.8 billion per week, or $8.4 billion in three weeks. During seven years in Afghanistan the United States spent $12.4 billion on foreign aid, reconstruction and training.
But the larger point is valid. According to congressional researchers, the United States has spent $653 billion over five years in Iraq and $171.7 billion over seven years in Afghanistan.
While Afghanistan has "benefited from bipartisan support," Thier said in an interview, "[t]he problem is we have not actually given it the priority it needs.
"The result," he said, "is we are seriously slipping backwards."