For months it's looked like the genocide in Darfur has fallen off the agenda of a White House desperately fighting fires in Iraq and throughout the Middle East. Yet last Monday President Bush's anger rocked the Oval Office when aides presented him with a plan for sanctions against the Sudanese government. Raising his voice, he demanded that his special envoy for Darfur, Andrew Natsios, and National Security Adviser Stephen Hadley come up with something stronger.

Or so I'm told. The result, according to several sources, is that the United States and Britain may finally make an effort, beginning this month, to push for serious punishment of the regime of Omar Hassan al-Bashir at the U.N. Security Council — and to shame the governments, such as China's, that have blocked multilateral action. Britain takes over Security Council chairmanship this week from South Africa, another resister of action on Darfur, while the United States' turn follows in May.

Bush and British Prime Minister Tony Blair have been feeding each other's passion on Darfur. They've decided "to stop watering down U.N. resolutions before they are even introduced," one official said. "This time they will ask for what they want," including both economic and military sanctions. As for China, which buys Sudan's oil and invests in its industry while shielding the government from international pressure, the official predicted: "There will be an international campaign against countries that are obstructing action by the council."

In the meantime, Bush is expected to approve more unilateral U.S. sanctions against Sudan, probably sometime after Easter. Among other steps, these will target assets of three Sudanese leaders and prohibit business in dollars with several dozen Sudanese companies, including an oil services firm. The United States could also help to rebuild former rebel forces in southern Sudan, which signed a peace deal with the government in 2005.

Why the tough action now? In part, Bush is said to be out of patience with Bashir, who has refused to accept a U.N. plan to deploy peacekeepers in Darfur to help protect the hundreds of thousands of refugees bottled up in camps. Under pressure from Arab leaders at a summit in Riyadh late last week, Bashir hinted that he would reconsider parts of the plan — but most likely he's stalling for time.

Bush and Blair are also feeling the effects of an international campaign for action on Darfur that has ranged from appeals from Hollywood stars and European intellectuals to petition drives and newspaper ad campaigns. The two leaders have talked about Darfur several times in recent weeks; at a European summit a week ago Blair declared the situation "intolerable" and the actions of the Sudanese government "unacceptable." He said the imposition of a no-fly zone over Darfur should be reconsidered — a step that could appear in the new Security Council resolution.

Curiously, the resolve of the two leaders has hardened at a moment when the situation in Darfur may be softening. Attacks by the Sudanese military have fallen off during the past several months — since Feb. 8 the United Nations has recorded only one, with no casualties. Assaults by government-backed janjaweed militias against civilians have also appeared to slacken. U.S. government and other Western analysts believe that Bashir has backed off from military operations, at least for now, because his army was unexpectedly bloodied by Darfur rebels in fighting in the fall.

Outside experts, such as John Prendergast of the International Crisis Group, think Bashir has not changed his scorched-earth policy for Darfur, merely his tactics. In recent weeks inter-communal fighting has erupted around the province, sometimes between rival Arab clans; Prendergast thinks the government has encouraged it. Though the level of mass killing is down, refugees are still pouring into camps — more than 80,000 since the beginning of this year, according to the United Nations. Meanwhile the government has been severely restricting the activity of aid organizations, a tactic it has used in the past to starve opponents into submission. Last week a new aid agreement was struck with international groups after the United Nations raised alarms; yet to be seen is whether Bashir will respect it.

It's possible that Bashir perceives the possibility of concerted international sanctions that could harm Sudan's booming oil industry, or a Western military intervention imposing a no-fly zone, and is trying to head them off. His country is vulnerable to sanctions; their use forced the settlement of the earlier civil war in the south. A U.N. envoy will be in Khartoum this week to test, again, the government's willingness to accept the plan for U.N. peacekeepers. If there's no breakthrough, we'll see if Bush and Blair can translate their passion into serious action.

Jackson Diehl is deputy editorial page editor for The Washington Post.