WASHINGTON — One week before the Iowa caucuses, the assassination of former Pakistani leader Benazir Bhutto pushed terrorism to the forefront in voters' minds and highlighted the candidacies of presidential hopefuls with long records on national security.

Bhutto's assassination on Thursday rippled through the presidential race as candidates scrambled to respond and adjusted campaign plans on a day overshadowed by the terrorist attack in Rawalpindi.

The deadly incident at an election rally in Pakistan could help presidential candidates such as Republican Rudy Giuliani, who was in charge of New York City when terrorists struck on Sept. 11, 2001, and Vietnam War veteran John McCain, a longtime member of the Senate Armed Services Committee.

On the Democratic side, Hillary Rodham Clinton has argued that her experience makes her prepared to lead the nation in troubled times. Rival Barack Obama has pushed a hard line in dealing with Pakistan and the search for Osama bin Laden.

At a high school in Lawton, Iowa, on Thursday, Clinton said she had come to know Bhutto during the former prime minister's years in office and her time in exile and was "profoundly saddened and outraged" by the assassination.

In a world of such violence and threats, Clinton said, "it certainly raises the stakes high for what we expect from our next president. I know from a lifetime of working to make change."

Giuliani said the assassination underscored a need for the U.S. to increase its efforts to combat terrorism.

"Her murderers must be brought to justice, and Pakistan must continue the path back to democracy and the rule of law," Giuliani said in a statement. "Her death is a reminder that terrorism anywhere — whether in New York, London, Tel-Aviv or Rawalpindi — is an enemy of freedom. We must redouble our efforts to win the terrorists' war on us."

McCain, in a statement, said the death of Bhutto "underscores yet again the grave dangers we face in the world today and particularly in countries like Pakistan, where the forces of moderation are arrayed in a fierce battle against those who embrace violent Islamic extremism.

"Given Pakistan's strategic location, the international terrorist groups that operate from its soil, and its nuclear arsenal, the future of that country has deep implications for the security of the United States and its allies. America must stand on the right side of this ongoing struggle," he said, noting that he has made numerous visits to Pakistan.

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