WASHINGTON (Reuters) - Striking a subdued tone on the fourth anniversary of the Iraq war, President George W. Bush pleaded for patience on Monday and warned skeptical Americans of dire consequences of a swift troop withdrawal.

Bush defended his Iraq policy in the face of new polls showing Americans increasingly oppose the war and Iraqis with little or no confidence in U.S. forces seemingly unable to halt sectarian bloodshed bordering on civil war.

With his approval ratings near the low point of his presidency, Bush made a brief televised appearance at the White House, appealing for more time for his plan to send in nearly 30,000 additional troops, mostly to stabilize Baghdad.

He acknowledged, however, that “prevailing in Iraq is not going to be easy.”

Bush’s cautious tone contrasted sharply with the swagger shown when he stood on the deck of an aircraft carrier weeks after the 2003 U.S.-led invasion that toppled Saddam Hussein and declared major combat operations in Iraq over.

As the war entered its fifth year on Monday, insurgents carried out deadly bombings in Kirkuk and Baghdad.

“Four years after this war began, the fight is difficult but it can be won,” Bush said after a teleconference with Iraqi Prime Minister Nuri al-Maliki. “It will be won if we have the courage and resolve to see it through.”

Bush said the Baghdad security plan is “in its early stages, and success will take months, not days or weeks.”

Bush did not repeat his earlier vow to achieve outright victory. But he stuck to his refusal to set a timetable for a withdrawal, despite stepped-up pressure from the Democratic-led Congress.

“It can be tempting to look at the challenges in Iraq and conclude our best option is to pack up and go home. That may be satisfying in the short run, but I believe the consequences for American security would be devastating,” he said.

The House of Representatives plans to debate a proposal that would tie approval of emergency war funds to a troop pullout by September 2008. Bush, who has threatened a veto, urged lawmakers to approve funding “without strings.”

‘WAR WITHOUT END’

“The American people have lost confidence in President Bush’s plan for a war without end in Iraq,” Democratic House Speaker Nancy Pelosi said.

House Republican Leader John Boehner accused the Democrats of a “slow-bleed scheme” to choke off support to the troops.

Bush said in January he was sending 21,500 more troops to Iraq, mostly to secure Baghdad, a number that has since climbed to around 30,000 with the addition of support troops.

A CNN poll showed support for the war had fallen to 32 percent, with 63 percent opposing it. Anti-war protests were mounted in U.S. cities over the weekend. Some 40 protesters were arrested outside the New York Stock Exchange on Monday.

Another poll showed four in five Iraqis have little or no trust in U.S.-led forces and most think their presence is making security worse. Despite that, only about a third want them to leave now.

President Bush delivers remarks on the fourth anniversary of the Iraq War, from the Roosevelt Room of the White House in Washington, March 19, 2007. REUTERS/Jason Reed

The poll, commissioned by the BBC, ABC News, USA Today and ARD German television, showed faith in U.S.-led forces was highest in the north, at 46 percent, and non-existent in Baghdad, where 100 percent said they had not very much or no confidence. Overall, just 18 percent of Iraqis expressed confidence.

Americans’ frustration over the Iraq war cost Bush’s Republicans control of Congress in November and is the main reason his public approval ratings are stuck near 30 percent.

Bush reiterated that premature withdrawal from Iraq would endanger the United States. “The terrorists could emerge from the chaos with a safe haven in Iraq,” he said.

His critics contend Iraq has distracted Washington from the war in Afghanistan, which they see as a more important fight.

The Iraq war has killed more than 3,200 U.S. military personnel and tens of thousands of Iraqis. Bombers struck in Kirkuk, to the north, on Monday, killing at least 12 people, and near a Shi’ite mosque in Baghdad, killing four.

Nearly three months after Saddam was executed, legal sources said his former vice president, Taha Yassin Ramadan, would be hanged on Tuesday for crimes against humanity.