(Adds Democratic response, paragraphs 10-11)

By Jeremy Pelofsky

CRAWFORD, Texas, Aug 25 (Reuters) - U.S. President George W. Bush, faced with growing calls to start withdrawing U.S. troops from Iraq, pleaded with Americans on Saturday for patience and cited progress in the past two months.

"The success of the past couple of months have shown that conditions on the ground can change -- and they are changing," he said in his weekly radio address. "We cannot expect the new strategy we are carrying out to bring success overnight."

Bush is facing mounting pressure from Democrats and a senior Republican lawmaker to begin pulling U.S. forces out of Iraq to show the government there that the American commitment is not open-ended.

Earlier this week, Bush drew parallels to the Vietnam War, raising the example of the emergence of the Khmer Rouge in Cambodia and violence in Vietnam after U.S. troops pulled out to warn of the consequences of leaving Iraq.

But, he acknowledged that despite increasing the number of troops in Iraq to tamp down the unrelenting violence, there was growing frustration that the government had not made much progress on political goals.

Still, Bush argued that young men were signing up for the Iraqi military, police were patrolling the streets and more operations with both U.S.-led troops and Iraqi forces were being conducted.

On Thursday, he suffered a setback when Sen. John Warner of Virginia, an influential congressional voice on military affairs in Bush's Republican Party, urged for an initial pullout of 5,000 troops who would be home by December.

Warner declined to back setting a withdrawal timetable but Democrats are expected next month to ratchet up pressure to do just that.

In about three weeks, Congress will receive a pivotal report on the state of war in Iraq by the U.S. commander on the ground in Iraq, Gen. David Petraeus, and the U.S. ambassador to Iraq, Ryan Crocker, which could trigger a change in Iraq policy.

Democrats argued the failures of the Vietnam War should not be ignored as the United States tries to chart its future course in Iraq but that U.S. soldiers could no longer bear the brunt of the failures by the Iraqi government.

"We can't expect our soldiers to continue to risk their lives especially when the Iraqi leaders themselves show no interest in achieving a peaceful political solution," Max Cleland, a former Democratic senator from Georgia and a Vietnam veteran, said in his party's weekly radio address.

Bush on Tuesday will try to build his case further for remaining in Iraq when he speaks to the American Legion annual convention in Reno, Nevada, the second of two such speeches.

"I will focus on the Middle East and why the rise of a free and democratic Iraq is critical to the future of this vital region and to our Nation's security," Bush said.

AlertNet news is provided by