PARIS — The Bush administration wants to spend about $10 billion for development and related aid to Afghanistan over two years, an amount roughly on par with recent American donations and sure to be the single-largest pledge at an international fund-raising conference.

The money is a mix of what Congress has already approved and what the administration is still seeking. Afghan leaders hope to raise between $15 billion and $20 billion in immediate help for their desperately poor, war-scarred nation. However, they face wide skepticism that the Kabul government is up to the task of seeing that the money is not squandered.

Secretary of State Rice said yesterday that worry about endemic corruption is “well-founded,” but she added that President Karzai of Afghanistan recognizes the toll corruption takes.

“President Karzai understands the corrosive nature of corruption and I think he’s looking for help,” Ms. Rice told reporters traveling with her to the French-sponsored donor session.

Mr. Karzai will try to persuade skeptical Europeans and other donors that he is serious about confronting rampant corruption throughout all levels of the government. Graft and thievery are taken for granted in daily life in Afghanistan, bleeding badly needed aid dollars and influencing what gets built and where.

Ms. Rice would not address long-standing corruption allegations involving one of Mr. Karzai’s brothers, saying she did not know enough about specific cases to comment.

Afghan officials are asking for $50 billion in aid over the next five years. Their development strategy, to be officially unveiled in Paris, envisions a peaceful Afghanistan by 2020.

America is the single largest donor to Afghanistan, not counting the cost of the ongoing war against Taliban insurgents.

A World Bank report released Tuesday said infighting within the Afghan government and a lack of leadership to confront graft “has resulted in the widely held view that corruption is being ignored or tacitly allowed.”

The report also called for increased efforts to oust government officials connected to the drug trade in Afghanistan, which is the world’s unrivaled center of heroin production.

Yet few dispute the need to support Mr. Karzai in developing a country where continuing deep poverty wins converts or paid fighters for the Taliban.

Despite about 65,000 foreign soldiers in Afghanistan — the highest number since the American-led invasion that toppled a Taliban regime in late 2001 — Mr. Karzai’s Western-backed administration has only a fragile grip on much of the country. The insecurity has hobbled development efforts.