WASHINGTON  Two weeks ago, senior Bush administration officials gathered in secret with Afghanistan experts from NATO and the United Nations at an exclusive Washington club a few blocks from the White House. The group was there to deliver a grim message: the situation in Afghanistan is getting worse.

Their audience: advisers from the presidential campaigns of John McCain and Barack Obama.

Over two days, according to participants in the discussions, the experts laid bare Afghanistan’s most pressing issues. They sought to make clear that the next president needed to have a plan for Afghanistan before he took office on Jan. 20. Otherwise, they said, it could be too late.

With American casualties on the rise and Taliban militias gaining new strength, experts on Afghanistan say the next president will need to decide swiftly if he intends to send more troops there, because even after deployment orders are issued, it could take weeks or months for American forces to arrive.

The next president will also face what could be politically fraught decisions about how aggressively to pursue a campaign against militants taking shelter in Pakistan’s tribal areas and whether to embrace negotiations under way in Afghanistan aimed at getting elements of the Taliban to lay down their arms. The discussions were started earlier this month in Saudi Arabia, and talks among Afghan officials and Taliban representatives have continued in Kabul at the request of President Hamid Karzai of Afghanistan.