The Asian Development Bank estimated in 2009 that the region would need as much as $8 trillion in investments in physical infrastructure by 2020 — an amount that exceeds what it or the World Bank can muster, experts at the two banks said.

Clay Lowery, a senior United States Treasury official from 2005 to 2009, said the Obama administration’s objections are not entirely well founded. The Chinese plan, he argued, “could be a positive development — potentially a great way to get Asian countries to work together on significant financial needs in the region.”

Last year, the United States said it would oppose financing of coal-fired power plants by the Asian Development Bank because of concerns about global warming. And early this year, Washington said it would not support construction of dams by the bank if they displaced people from their homes.

“Energy is one of the biggest needs of economic growth in Asia, and China will be able to promise projects without these hindrances,” said a senior A.D.B. official, who spoke on condition of anonymity because the bank does not want to be seen in a public spat with China. The Manila-based bank has become so encumbered with restrictions that it now takes up to seven years on average for a project to go from proposal to approval to completion, the official said.

He added that the bank, worried about competition from the Chinese, has begun looking at ways to streamline its procedures. The A.D.B. has reason to be anxious, he said, because the $50 billion in capital planned by China would immediately make the new bank a significant competitor. China has also told prospective members that it expected another $50 billion from financial institutions and private capital. By comparison, the A.D.B. has about $78 billion in capital, including retained earnings and borrowings.

The Chinese government has tapped one of its top finance officials, Jin Liqun, the former head of China’s sovereign wealth fund and a former senior official at the A.D.B., to lead the new bank.

In a sign of the discord between Washington and Beijing over the bank, Mr. Jin met in August with the United States ambassador to China, Max Baucus, and bluntly told him to tell Washington to soften its opposition to the bank, a senior Obama administration official familiar with the encounter said.