President Obama plans to appoint a close adviser and retired general to be his special envoy to Sudan as the administration ratchets up pressure against the government in Khartoum for expelling humanitarian relief organizations from the ravaged region of Darfur, administration officials said Tuesday.

Obama will tap Maj. Gen. J. Scott Gration, a Swahili-speaking retired Air Force officer who grew up in Africa as the son of missionaries, to take on one of the most delicate diplomatic missions of his presidency, according to three administration officials, who were not authorized to discuss the selection before the official announcement on Wednesday.

Secretary of State Hillary Rodham Clinton escalated the administration’s oratory on Tuesday, vowing to hold President Omar Hassan al-Bashir of Sudan responsible for the expulsion of aid groups.

"This is a horrendous situation that is going to cause untold misery and suffering for the people of Darfur, particularly those in the refugee camps,” she told reporters.

"The real question is what kind of pressure can be brought to bear on President Bashir and the government in Khartoum to understand that they will be held responsible for every single death that occurs in those camps.”

The sharper tone and the appointment of General Gration come after criticism from activists who once saw Mr. Obama and his team as allies in the struggle to save the people of Darfur.

During the presidential campaign, Mr. Obama lamented the "stain on our souls” left by the mass death in Darfur and vowed "never again.”

Mrs. Clinton called for a no-flight zone. And Susan E. Rice, a top Obama adviser, even envisioned a bombing campaign to save victims.

But with the first major new humanitarian crisis on Mr. Obama’s watch, advocates complained that the urgency of the campaign trail had given way to inertia, infighting and inaction.

More than one million Darfuris are at risk while the new administration debates what to do, the advocates said. "Why is there a disconnect?” asked Jerry Fowler, the president of the Save Darfur Coalition, an umbrella organization, recalling Mr. Obama’s strong words as a candidate. "We need presidential engagement and we need it now.”

The latest crisis in Darfur represents an early foreign test for a new president consumed by economic strife at home. Advocates and policy makers said the administration appeared to be locked in a struggle over who would take charge of the issue and how it should be approached.

Rather than taking firmer action now, they said, the administration is still waiting for a comprehensive review of Sudan policy.

"If the president believes the rhetoric he used, and I think he does, he’s being ill advised by not moving on this,” said Richard S. Williamson, the last United States special envoy to Sudan. "Drift works in the favor of those who are committing atrocities.”

Administration officials rejected the criticism, pointing to what they called quiet diplomacy, working with governments from France, Britain, Uganda and Egypt to put pressure on Sudan to reverse the expulsion of the aid groups.

The more muscular tactics they advocated before joining the government, they said, are still on the table for the broader review of Sudan policy, but would not be effective in the current humanitarian crisis.

I feel as former activist and current official that we have focused on the right thing here, which is trying to save lives,” Ms. Rice, now the ambassador to the United Nations, said in an interview.

"The notion that we haven’t been active — it is just false, downright false. Quite the contrary. What we haven’t done is a lot of bluster and public threats.”

The latest crisis began March 4, when the International Criminal Court in The Hague charged Mr. Bashir with seven counts of war crimes and crimes against humanity stemming from the slaughter of 300,000 people in Darfur, the first such indictment of a sitting head of state by the tribunal.

Mr. Bashir then expelled 13 nongovernmental organizations, including Doctors Without Borders, CARE, Oxfam Great Britain and Save the Children, accusing them of spying for the court. Some groups had offices broken into and equipment seized.

As a result, relief groups said, more than one million people are without adequate food, clean water and health care as a meningitis outbreak looms.

United Nations workers remain, but Mr. Bashir said Monday that he wanted all foreign relief organizations out within a year.

The Obama administration denounced the expulsions. After a meeting with Ban Ki-moon, the United Nations secretary general, Mr. Obama called the Darfur crisis one "that we care about deeply” and said it was important "to send a strong, unified, international message that it is not acceptable to put that many people’s lives at risk.”

Mr. Obama came to office with a team particularly versed on Darfur. Aside from Mrs. Clinton and Vice President Joseph R. Biden Jr., both of whom dealt with the issue in the Senate, Mr. Obama installed Ms. Rice, a vocal advocate for tougher action on Darfur, at the United Nations. Analysts said Mr. Bashir was trying to stare down Mr. Obama and get the indictment suspended.

John Norris, executive director of the Enough Project, an antigenocide group, said the administration must decide whether to force Sudan’s government to let the relief agencies back in. "Or is it going to be willing to accept talking about the situation and seeing if that’s enough?” he asked.

"There’s a real decision moment for a new president.”

Source NEWYORK TIMES