Ahead of his firsthand look at the tsunami's devastation, Secretary of State Colin Powell (search) said Sunday the United States has responded appropriately to what he called one of the world's greatest catastrophes.

Powell, whose Asia trip includes stops in Thailand (search), Indonesia (search) and perhaps Sri Lanka (search), defended the Bush administration against criticism it reacted slowly to the crisis with an initial pledge of $35 million, since increased to $350 million.

"We have nothing to be embarrassed about. Our response scaled up as the scope of the disaster scaled up," he said.

Lawmakers said Congress stands ready to commit more money — potentially in the billions of dollars — and work with President Bush when he makes such a request. They also said an outpouring of U.S. aid could help rehabilitate America's image among Muslims abroad in the wake of the Iraqi war.

"Political opportunity" exists for the United States in how the country lets the Muslim world know "that our humanitarian instincts are across the board, that the whole world is our concern, not just the non-Muslim world, and that we view the Muslim world as an essential part of the whole world community," said Sen. Carl Levin, D-Mich.

Powell's delegation includes Florida Gov. Jeb Bush (search), Andrew Natsios, administrator for the U.S. Agency for International Development (search), and Mike Brown, director of the Federal Emergency Management Agency.

"We are going to be meeting with the countries in the region and international organizations that are at work in the region to see what more we can do to assist with this relief effort. It is one of the most massive relief efforts ever mounted in response to one of the worst catastrophes the world has ever seen," Powell said on a political talk show.

Powell said he will participate in a meeting Thursday in Jakarta, Indonesia, of the Association of Southeast Asian Nations to develop a strategy to help with relief efforts.

"The question right now is not money. There is a lot of money available. The question is how do we use that money, not only for immediate relief, but for long-term reconstruction," Powell said.

The secretary said he will go to the Thai resort of Phuket (search) and hoped to visit the ruined provincial capital of Banda Aceh (search), where elephants have been brought in to help remove debris. On his return home, Powell said he would try to stop in Sri Lanka.

Bush, who returned to the White House on Sunday after a holiday vacation at his Texas ranch, will get reports from the delegation, but does not now intend to go to the region.

"These are nations that are spending their time and attention now delivering relief to their citizens, and a visit by the president of the United States, with all that entails, would be a diversion of their attention from providing support," Powell said.

"So we don't need a big, grandstanding event right now, which would essentially, no matter if it's only two capitals, be a significant diversion," he said.

Jeb Bush, who has overseen Florida's recovery from hurricanes, said before leaving Miami, "I know the president has deep concerns about what has happened and the fact that I am his brother symbolically may underscore his deep concern."

The U.S. death toll stands at 15, with eight dead in Thailand and seven in Sri Lanka. But Powell said there are "several thousand" Americans that the government is waiting to hear from — directly or through families.

Powell said he doesn't expect a huge number of American casualties because he hasn't heard of large numbers of families coming to the State Department or U.S. embassies suggesting that they fear the worst. "They've just not been able to reach out to their loved one or their loved one is not able to reach out to them," he said.

Sen. Richard Lugar, chairman of the Senate Foreign Relations Committee, said the $350 million that Bush has committed represented the amount of disaster aid in the current federal budget. "President Bush took awhile to identify that money, but nevertheless, having done so, he's pledged it all," Lugar, R-Ind., said on "Fox News Sunday."

Added Levin, the top Democrat on the Senate Armed Services Committee: "I think now we appear to be on the right track. But the first few days were disappointing, and not in keeping with the great American tradition and generosity."

Powell emphasized that the Defense Department is spending tens of millions of additional dollars to get supplies to victims of the tsunami in what has become the largest U.S. military operation in the region since the Vietnam War.

"I think we've responded rather aggressively and appropriately. And the American people should be pleased and proud of the way we've done it," the secretary said.

Powell also said, "I will tell you who is not churlish or disappointed in our response, and that's the nations who are receiving aid. They have been very thankful and very appreciative of what we have done. And we will do more."