OMAHA — Democratic presidential candidate Joe Biden rebuked President Bush’s Iraq war speech hours before it was to be delivered on Thursday, saying the idea that the troop surge was working was “preposterous.”

“We must begin to take American troops out now because it takes a long time to get them out,” Biden said.

Bush was set to ask Americans for patience to let his Iraq strategy succeed, but Biden said the surge was not making Americans any safer and was putting military lives at risk for no strategic gain.

“He’s going to say that when the surge finally ends next year that we’ll be right back to where we started,” Biden told reporters at the University of Nebraska at Omaha. “No lasting change on the ground, and no end in sight. This, quite frankly, … is unconscionable.”

The U.S. senator from Delaware said the mission in Iraq should be focused only on fighting al-Qaida, training Iraqis and protecting the country’s borders.

Biden also reiterated his idea to divide the country along ethnic lines with a limited central government that would distribute oil revenues and perform other central functions.

Biden said that if troops were withdrawn without a political settlement, the situation would deteriorate into a regional war involving Iran, Syria and Turkey.

Biden stood out two days ago as chairman of the Senate Foreign Relations Committee, when he moderated as senators — including several presidential candidates — questioned the top U.S. general in Iraq about the war.

Thursday, Biden said Democrats should get together behind a comprehensive plan.

“I don’t care whose it is. I don’t care how they phrase it. I don’t care who gets credit for it,” he said. “Ending this war in Iraq and saving American lives and securing our future is a heck of a lot more important than whether Joe Biden or Barack Obama is elected president of the United States of America.”

Earlier in the day, Biden picked up an endorsement from Iowa House Majority Leader Kevin McCarthy, who said he based his decision on Biden’s Iraq plan and foreign policy experience.

When asked by reporters how important foreign policy experience would be in the next election, Biden said that would be for voters to decide.

But, Biden said, “If you don’t know what your comprehensive notion of America’s place in the world is at this moment in our history, if you’re not more knowledgeable than your own secretary of state, if you don’t have a clear sense of where you wish to take the world, I think America’s in trouble.”

Biden has numerous campaign events scheduled in Iowa through Sunday.