President Bush is urging Iraqis to renounce sectarian violence the day after suspected al-Qaida militants bombed a revered Shi'ite shrine in Samarra. VOA White House Correspondent Scott Stearns reports, Mr. Bush is warning of more casualties ahead as the full force of his troop surge takes effect.

A picture shows destroyed Shiite Imam Askariya shrine in the restive city of Samarra, north of Baghdad, 13 June 2007

President Bush says Wednesday's attack on the Askariya shrine was a provocative act of cruelty that reveals terrorists as the enemy of every Iraqi who seeks to live in peace.

"These killers hope that their attacks, like this one, will create enough confusion and chaos that we will abandon this young democracy," he said.  "They have objectives. They have goals. They want to drive us out."

The president says it was the sectarian violence that followed last year's destruction of the golden dome of the mosque that forced him to decide between withdrawing U.S. troops or reinforcing them.

Mr. Bush chose reinforcement, ordering another 30,000 Americans to Baghdad and al-Anbar province. He says it is too early to judge whether that troop increase is working, but with the last of five reinforcement brigades expected to become fully operational this week, the president says it is a critical period for the new strategy.

President Bush gestures to the crowd to be seated as he arrives to deliver remarks to the Associated Builders and Contractors in Washington, 14 June 2007

"We can expect heavy fighting in the coming weeks," he added.  "We can expect more casualties, both American and Iraqi casualties."

In remarks to a convention of building contractors, Mr. Bush said the more than 3,000 Americans who have died in this war were fighting to make the nation safer, because he says terrorists would use a victory in Iraq to launch more attacks against the United States.

Public opinion polls say a majority of Americans now believe that invading Iraq was a mistake. A Los Angeles Times poll this week shows more than two-thirds of those surveyed disapprove of how the president is handling the war.

Congressional Democrats are threatening to block further funding for the war unless there is progress by September.

President Bush again criticized those who are calling for a troop withdrawal.

"It's a difficult fight, and the temptation is to look for an easy way out," he explained.  "Some in Washington want to declare defeat before our troops even have the chance to make it work. The consequences of failure would be grave."

Mr. Bush says losing in Iraq would create a dangerous security vacuum in which sectarian violence would multiply on what he calls a horrific scale that could engulf the entire region.