WASHINGTON – President Bush, confronting congressional demands for timelines to withdraw U.S. forces from Iraq, began the fifth year of the war seeking from wary Americans what he has sought many times before: patience.

In a brief address from the White House on Monday marking the fourth anniversary of the U.S.-led invasion in 2003, Bush’s appeal acknowledged a backdrop of continuing violence in Iraq, the mounting challenge from the Democratic-run Congress and public sentiment that has taken a turn against a conflict that has cost more than 3,200 American lives.

“Prevailing in Iraq is not going to be easy,” Bush said. “Four years after this war began, the fight is difficult, but it can be won. It will be won if we have the courage and resolve to see it through.”

The president’s plea came as Democratic leaders of the House prepared to debate a $100 billion boost in war spending in a bill that also demands timeframes for troop withdrawals – a bill that the White House promises Bush will veto if it contains any deadlines.

In the anniversary war debate, Senate Majority Leader Harry Reid, D-Nev., offered this: “As we enter the fifth year of the war, the core question Americans should be asking themselves today is whether the administration’s approach in Iraq has made America more secure. The answer is clearly no.”

Sen. John Kerry, D-Mass., Bush’s 2004 presidential election foe, said, “Patience is not a strategy.”

Secretary of State Condoleezza Rice earlier Monday defended going to war. However she also acknowledged that the administration should have sent more troops initially to contain the civil strife.

Asked on CBS’s “The Early Show” to outline what the administration could have done better, she said that, in the early days, officials “might have looked to a more localized, more decentralized approach to reconstruction.”

Bush made his plea in the midst of an escalation of U.S. forces, with the president adding nearly 30,000 troops to a total deployment that will near 160,000 by early summer.

“Success will take months, not days or weeks,” Bush said of his newest plan for securing order in Baghdad, a plan first outlined in a nationally televised address in January.

“There will be good days and there will be bad days ahead … as the security plan unfolds,” Bush said in his second televised address this year from the Roosevelt Room of the White House, a portrait of a rough-riding Teddy Roosevelt above the fireplace behind him.

The president said there were “some hopeful signs” in Iraq, such as the Iraqi government’s deployment of additional army brigades for the new security plan for Baghdad.

Bush somberly read from a text, yet appeared to grow more animated as he addressed the looming debate in the House.

“They have a responsibility to ensure that this bill provides the funds and the flexibility that our troops need to accomplish their mission,” he said. “And they have a responsibility to get this bill to my desk without strings and without delay.”

The White House also promised, as it has before, what the president will do with a war-spending bill containing any withdrawal deadlines.

Press secretary Tony Snow elaborated on Bush’s remarks: “What he’s saying is that if they attach strings, he will veto it.”

Six months into the war, in September 2003, a solid majority of Americans supported the idea of keeping troops in Iraq – 63 percent of those surveyed by the Washington-based Pew Research Center.

Yet in February, just 42 percent backed keeping troops in Iraq, according to the Pew survey, which has tracked a steady decline in public support over four years. While 32 percent of the public said in 2003 that the U.S. should bring troops home, that number had risen to 53 percent in February.

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

Just as he appealed for patience in the war on terror after Sept. 11, the president has repeatedly punctuated both successes and setbacks in the war in Iraq with such pleas.

Addressing the American Legion in Salt Lake City last summer, Bush said, “For all that is new about this war, one thing has not changed: Victory still depends on the courage and the patience and the resolve of the American people.”