Thousands of Americans have held large public demonstrations around the United States to show their concern about the ongoing violence in the western Sudanese region of Darfur. In Washington movie stars, athletes and politicians headlined the largest event.

Protesters on the National Mall in Washington, DC voicing their concern about genocide in Darfur

Former Marine Captain Richard Steidle just completed a cross-country U.S. tour aimed at raising public awareness of the violence in Darfur. He spoke to a crowd of thousands of people at a rally on the National Mall in Washington D.C.

"We have the power, here in America, the people have the power, to stand up and say, 'genocide. never again,' " said Richard Steidle.

Since fighting broke out between rebel groups and government-backed militia groups in Darfur in 2003, more than 180,000 people have been killed and more than two million others have been driven from their homes. The rebels, from black African farming villages, accuse the Arab-dominated Sudanese government of discrimination and oppression.

Samantha Power, who has written about genocide, told the demonstrators in Washington their numbers will not only draw the attention of American politicians, but will be noticed in Khartoum.

"The Sudanese government knows you are watching," said Samantha Power. "This is the first time in the history of genocide that a perpetrator has so known that they've got America looking over their shoulder."

Among the speakers, Holocaust survivor and Nobel laureate Elie Wiesel linked the atrocities in Darfur to terrorism, and pointed to recent comments by Iranian president Mahmoud Ahmadinejad, who called into question the truth of the Holocaust.

"We are here because if we do nothing, al Qaida and the world's number one Holocaust denier, the infamous president of Iran, Ahmadinejad, will send terrorists there," said Elie Wiesel. "We are here to raise our compassion and our anger at leaders who are timorous, complacent and unwilling to take risks. We want them to take risks and stop the massacre."

Sunday's rallies, in Washington and nearly 20 other cities around the United States, were organized by the Save Darfur Coalition, an alliance of more than 100 faith-based, humanitarian and human rights organizations.

Meanwhile, Secretary of State Condoleezza Rice told CNN's "Late Edition" President Bush is "passionate about what is going on in Darfur." The U.S. government has officially labeled it a genocide and has frozen the assets of four people connected with the Darfur violence.

Rice said Washington has been actively pushing for a peace settlement there and for what she called "a more robust" international security force in Darfur. But she added the United States cannot act alone.

"We need more help from the international community," said Condoleezza Rice. "We need more help from China and Russia, which I think need to look at what is going on there and ask what they can do. And, we frankly need to make sure that the African Union acts expeditiously to take advantage of the help that is being offered by the United Nations and by NATO."

Later this year, U.N. peacekeepers are due to take over security duties from African Union soldiers, although the United Nations has accused the Sudanese government of blocking transition efforts.

Prior to the rallies, the Sudanese embassy issued a statement calling them "naive" and "misdirected." The statement said the large show of American public attention to the issue sends what Khartoum says is the "wrong message" to the rebels.