The following op-ed by Adam Sterling and Sam Bell appeared in Monday's Fort Worth Star-Telegram.

"Not on my watch."

In September 2001 President Bush scrawled these now famous words on the margins of a presidential briefing highlighting the Clinton administration's failure to respond to the genocide in Rwanda. The United States -- along with its European allies -- failed to lift a finger as more than 800,000 people died in less than 100 days.

Three years after pledging not to repeat Clinton's mistakes, President Bush declared that genocide was occurring in the Darfur region of Sudan, the first time a sitting U.S. president had labeled an ongoing conflict as genocide.

Although his foreign policy record is often criticized, Bush has, at times, shown commendable leadership on Sudan. In 2005 he was at the forefront of a peace deal that brought the north and south of Sudan together after two decades of civil war. Since the eruption of the genocide in Darfur, Bush has imposed a number of economic sanctions against the Sudanese government and has been an outspoken critic of the government's policies in Darfur.

Leadership on Sudan is needed now more than ever. As many as 400,000 Darfuris have been killed, and there are now more than 3 million refugees displaced throughout Darfur and neighboring Chad.

In July the United Nations Security Council approved a robust international peacekeeping force to deploy by the end of this year. That force, because of obstruction from the Sudanese government and member states' failure to contribute resources, is far from full strength.

Meanwhile, the United Nations reports increases in violence, including ground attacks and aerial bombardments by Khartoum and its allied militias.

So how can we pressure the Sudanese government to support the deployment of peacekeepers?

Since coming to power in a military coup, the Sudanese regime has ignored diplomatic pleas and violated international obligations, but when faced with sustained and serious economic pressure it has caved. After the United States imposed sanctions against Khartoum in 1997, the regime cut ties with Osama bin Laden, who was provided safe haven in Sudan from 1993 to 1996, and other terrorist elements within the government.

Today, American activists are using economic pressure on Khartoum to help end genocide in Darfur. Texas is among 22 states that have passed divestment measures, committing to sell investments in foreign companies that enable the Sudanese war machine.

Roberta Cohen, a senior adviser at the Brookings Institution, recently found that, "In the view of some analysts, divestment campaigns may prove more effective than sanctions. ... The Sudanese government has publicly urged an end to divestment actions, underscoring the potential sting of their impact."

Considering Bush's leadership, the dire situation on the ground, and the vulnerability of the Sudanese government to economic pressure, Americans concerned about Darfur were shocked when the president publicly opposed the most robust piece of Darfur legislation to come out of Congress, the Sudan Accountability and Divestment Act.

The legislation, which was approved unanimously this month by both chambers of Congress, would authorize and provide legal protection for state and local governments to divest and would prohibit problematic companies in Sudan from receiving federal contracts.

The people of Darfur need our leadership more than ever. By signing the Sudan Accountability and Divestment Act, President Bush can send a message to the Sudanese government that genocide will not occur on his watch and it will not occur on his dime. Call 1-800-GENOCIDE and ask President Bush to sign the Sudan Accountability and Divestment Act.