One week before the Iowa caucuses, the assassination of former Pakistani leader Benazir Bhutto has pushed terrorism to the political forefront.

Democratic presidential hopeful Hillary Rodham Clinton says she's "profoundly saddened and outraged" over the killing of Bhutto. Clinton says she had come to know Bhutto during the former prime minister's years in office.

Democrat Barack Obama says he's shocked and saddened by Bhutto's death, calling her "a respected and resilient advocate for the democratic aspirations of the Pakistani people."

Republican Rudy Giuliani says the assassination underscores a need for the United States to increase its efforts to combat terrorism.

Fellow Republican John McCain, in a statement, says the death of Bhutto "underscores yet again the grave dangers we face in the world today."

Former Massachusetts Governor Mitt Romney focused on the threat of "global, violent radical jihadism."

Republican candidate Mike Huckabee calls the assassination "devastating news for the people of Pakistan, and my prayers go out to them."

And the White House says it expects an open review into Bhutto's assassination.

White House spokesman Scott Stanzel says the Bush administration is willing to work with Pakistan to make sure a thorough investigation takes place.

He noted that President Bush has spoken by phone with Pakistani President Pervez Musharraf, but had no further details. He also said that it's up to Pakistan to determine whether to move forward with its upcoming parliamentary elections.

Meanwhile, Secretary of State Condoleezza Rice is urging Pakistanis to remain calm. Rice says the attack will "no doubt" test the will and patience of Pakistan's people. But she's calling on citizens and political leaders to "work together to build a more moderate, peaceful, and democratic future."