Presidential contender Barack Obama on Tuesday dismissed his Democratic rivals' change of heart on the Iraq war as too little too late, while Hillary Rodham Clinton urged a quick end to U.S. involvement in the conflict.

Obama and Clinton focused on the nearly 4 1/2 year war in dueling speeches only a few city blocks apart in the first-in-the-nation voting state of Iowa. Senators will have a chance to vote the coming days on whether to begin withdrawing U.S. forces from Iraq where the conflict has claimed more than 3,600 U.S. lives.

"It will be enormously difficult to invest in jobs and opportunity until we stop spending $275 million a day on this war in Iraq," Obama said in prepared remarks obtained by The Associated Press. "I believed then and still do that being a leader means that you'd better do what's right and leave the politics aside, because there are no do-overs on an issue as important as war."

Obama, then a state lawmaker in Illinois, opposed the war from the start. Clinton voted in 2002 to give President Bush the authority to launch the invasion to topple Saddam Hussein's regime.

"Our message to the president is clear," said Clinton, in remarks prepared for delivery. "It is time to begin ending this war — not next year, not next month — but today."

Throughout the campaign, the two — who have raised more money than their rivals and rank high in most opinion polls — have debated the nuances of their opposition to the war. Obama has made it clear he was opposed to the war from the beginning, implicitly drawing a distinction between his record and Clinton's vote to authorize the war.

For her part, Clinton has said that if she knew now what she knew when the initial vote was taken, she would have opposed the war and she has voted against continued funding. She emphasized that point in her campaign speech Tuesday.

"We have heard for years now that as the Iraqis stand up, our troops will stand down," said Clinton. "Every year we hear about how next year they may start coming home."

The New York senator dismissed Bush view that the administration's troop surge should be given time to work.

"Now we are hearing a new version of this yet again from the president as he has more troops in Iraq than ever and the Iraqi government is more fractured and ineffective than ever," said Clinton.

Obama was in Iowa for what aides had described as a speech on jobs and the economy, but he made it clear that the war in Iraq overshadowed all other issues.

The Illinois senator sought to bring home the cost of the war, noting that taxpayers in the congressional district from which he spoke would pay $756.6 million to finance the war by the end of this year, enough to provide health care to 238,000 adults and 339,000 children.

"We are about to receive yet another report telling us that Iraq's political leaders have not met a single goal they set for themselves to demonstrate any kind of progress towards stability. Not one goal," Obama said. "Well, they have had their chances and George Bush has had his — we cannot keep our troops in the middle of a civil war that Iraq's leaders refuse to end. It's time to bring them home."

Clinton echoed much the same theme in her speech.

"Well, the right strategy before the surge and post-escalation is the same," said Clinton. "Start bringing home our American troops now."

Iowa's precinct caucuses next winter traditionally launch the presidential nominating season, and most polls have shown Clinton, Obama and former Sen. John Edwards fighting for the lead.