White House hopeful Barack Obama on Saturday said private security contractors in Iraq are raising the risk for U.S. troops because Iraqis don't distinguish between the forces.

He also criticized the pay disparity between soldiers and private contractors, saying the contractors get paid nine times as much as those in uniform.

"You've got young men and women signing up to serve, willing to spill blood for America. How could they be treated less well than private contractors?" Obama told a crowd of more than 1,400 at a high school gymnasium in this early voting state.

"And these private contractors, they go out and they're spraying bullets and hitting civilians and that makes it more dangerous for our troops," Obama said.

Blackwater USA, the private contractor that provides heavily armed security for U.S. diplomats serving in Baghdad, has been under intense scrutiny in recent weeks. Security forces employed by the company are accused of killing 13 Iraqi civilians in a violent incident in central Baghdad last month. North Carolina-based Blackwater — which Obama did not mention by name — contends its employees came under fire first, but the Iraqi government and witnesses have disputed that, saying the guards opened fire without provocation.

Earlier Saturday in Ottawa, Ill., Obama told a crowd of about 600 that when "this war is over, we can finally get back to facing the challenges we face here at home, the challenges you're grappling with every day."

The first-term Illinois senator said the war now costs between $10 billion and $12 billion a month. He noted that President Bush had vetoed a $35 billion measure expanding a children's health program and wants almost $190 billion for military operations in Iraq and Afghanistan.

Obama reminded the crowd of United Auto Workers members in Illinois and the crowd in Aiken that he opposed invading Iraq at a time when most other politicians — including chief rivals Hillary Rodham Clinton and John Edwards — supported it. Obama expressed his opposition in the fall of 2002 when he was a state senator and considering a run for the U.S. Senate.

"We need to ask those who voted for that war, 'How could we give the president a check and then be surprised when he decides to cash it?"' Obama told the South Carolina crowd.

He said he'd pull a division or two of U.S. troops out of Iraq every month and leave only enough there to do protect the embassy and diplomats.

Obama wrapped up the evening in Rock Hill, S.C., where he told a crowd of more than 2,000 that Clinton had criticized him for being willing to meet with leaders in Iran and Venezuela. Clinton claimed "you'll lose a propaganda war" by talking with them, Obama said.

"I am not worried about losing a propaganda battle with some petty tyrant," he said.

He also said there are "folks in al-Qaida who we can't negotiate with. We've got to take them out. I will not hesitate to do what is necessary to protect the United States of America."

Obama was finishing his South Carolina swing by attending services at a Greenville church Sunday morning.