Investor concern about the future of banks, including Citigroup, have been one issue weighing heavily on the stock market. Financial shares continue to be among the worst hit, despite the trillions that governments are spending to try and restore the system. Citigroup shares, for example, closed at $1.03 on Friday; two years ago, the stock was trading at $55 a share.

The Treasury department made its own news on Sunday, filling three of the top positions under Secretary Timothy F. Geithner. Alan B. Krueger was named as assistant secretary for economic policy; Davis S. Cohen was chosen as assistant secretary in the office of terrorism and financial intelligence, and Kim N. Wallace was named assistant secretary for legislative affairs. The announcements addressed growing concerns that even as the Treasury Department has worked furiously to craft bank bailouts over its first six weeks, the department still had left key positions unfilled. The withdrawal last week of Annette Nazareth, Mr. Geithner’s prospective deputy and a former commissioner at the Securities and Exchange Commission, touched off questions about whether staffing problems might be slowing the administration’s response to the economic crisis. The position of deputy treasurer remains open.

Robert Gibbs, the White House press secretary, played down the personnel matter.

“We have tremendous confidence in Secretary Geithner,” he said at a news conference on Thursday, “and we are working with the committees of jurisdiction in order to get nominees both up to Capitol Hill and through the process of getting them into government.”

Pressed about the reason for delay, he said that nominees were being subjected to “a very rigorous process  and we’re doing it, with all involved, as quickly as we can.” In response to the crisis in the banking system, the Treasury is pursuing a strategy that seeks to avoid either the failure or nationalization of the biggest banks. In declaring his support for closing giant financial institutions, Mr. Shelby pointedly disagreed with the position taken by Senator Lindsay Graham, a fellow Republican, who suggested two weeks ago, also on “This Week,” that the banks may need to be nationalized.

Mr. Obama made clear in an interview published Sunday in The New York Times that he did not want any of the biggest banks to fail, saying his administration “would take more significant action to deal with those institutions.” “But the point is that our commitment is to make sure that any actions we take to maintain stability in the system, begin to loosen up credit and lending once again so that businesses and consumers can borrow,” he said. “And if they can, then you’re going to start seeing businesses invest once again and you’re going to see people hired once again, but it’s going to take some time.”