With Congress out of town, Mr. Bush tried to take the upper hand over Democrats who are making increasing forays into foreign policy as his term heads towards its end and his approval ratings remain low.
Democrats, buoyed by recent Republican defections from Mr. Bush on Iraq, shot back that they are the ones pursuing effective solutions overseas in response to a national desire for change from his approach.
"We are not going to allow the president to continue a failed policy in Iraq. We represent the American people's vision on this failed war," Senate Majority leader Harry Reid, D-Nev., said at a ceremony for a new Nevada National Guard armory near Las Vegas. "We have said time and time again the troops will have everything they need."
Presidential Historian Douglas Brinkley said Democrats believe they have nothing to lose by confronting the president, reports CBS News correspondent Wyatt Andrews.
"They're taking the posture that Bush is not just a lame-duck president, but is irrelevant and wrong. And I think this is a very significant, historic day," he said.
Speaking a day before he heads out of town for six days for events in the West and an Easter break at his ranch, the president said Democrats are failing their responsibility to the troops and the nation's security by leaving for their own recess after passing bills to fund the war that contain timelines for American withdrawal.
Given his promised veto of anything containing a deadline — and the likelihood that his veto would be sustained on Capitol Hill — Mr. Bush said Democrats are merely engaging in games that "undercut the troops."
"Democrat leaders in Congress seem more interested in fighting political battles in Washington than in providing our troops what they need to fight the battles in Iraq," Mr. Bush said. "In a time of war, it's irresponsible for the Democrat leadership — Democratic leadership in Congress to delay for months on end while our troops in combat are waiting for the funds."
Nearly two months ago, Mr. Bush asked for more than $100 billion to pay for the wars in Iraq and Afghanistan this year. Congress has approved the money, but the Senate added a provision also calling for most U.S. combat troops to be out of Iraq by March 31, 2008. The House version demands a September 2008 withdrawal.
These bills still must be reconciled before legislation can be sent to the president.
"They need to come off their vacation, get a bill to my desk, and if it's got strings and mandates and withdrawals and pork I'll veto it," the president said. "And then we can get down to the business of getting this thing done."
Not so fast, Democrats responded.
"Americans want compromise, not a cowboy-style showdown," said House Majority Whip James Clyburn, D-S.C.
Fresh from a briefing by Defense Secretary Robert Gates, the president sought to put pressure on Democrats by detailing ways that delaying the money could harm troops and their families.
After the current $70 billion war appropriation runs out in mid-April, Mr. Bush said, the military would have to consider cutting back on equipment, repairs and training for National Guard and reserve forces. After mid-May, he said, more steps would be considered, such as delaying or curtailing the training of some active duty forces.
Despite Mr. Bush's warnings, dire consequences can be avoided even after the money starts to run out. It has become routine in recent years for Pentagon accountants to move money around in the department's half-trillion-dollar budget to make sure operations in Iraq and Afghanistan are not disrupted. The money is repaid, usually with minimal disruption, when the president signs a new war spending bill.
According to the nonpartisan Congressional Research Service, Mr. Bush and Congress have about three months to resolve their standoff before Iraq operations would actually be affected.
Democrats told Mr. Bush to stop blaming them for being the ones to keep money from soldiers, and to start negotiating.
"If President Bush vetoes funding for the troops, he will be the one who is blocking funding for the troops. Nobody else," said presidential candidate John Edwards.
On another topic, the president took issue with a two-day stay in Syria by Pelosi that began Tuesday.
As the speaker donned a head scarf and mingled with Syrians at a mosque and a market in Damascus' Old City, preparing for meetings Wednesday with Syrian President Bashar Assad, Mr. Bush said she was sending dangerous signals. State-run newspapers in Syria published news of the visit on their front pages, with one daily publishing a photograph of Pelosi next to the headline: "Welcome Dialogue."
President Bush called the meeting counterproductive, warning that it sends mixed signals, reports CBS News senior White House correspondent Bill Plante.
"Photo opportunities and/or meetings with President Assad lead the Assad government to believe they're part of the mainstream of the international community, when, in fact, they're a state sponsor of terror," he said.
Mr. Bush added that meetings with many high-level Americans have done nothing to persuade Assad to control violent elements of the militant groups Hamas and Hezbollah, to halt efforts to destabilize Lebanon or to stop allowing "foreign fighters" from flowing over Syria's border into Iraq.
The bipartisan Iraq Study Group recommended that the U.S. begin direct and extensive talks with Syria and Iran over Iraq. The Bush administration has long rejected that idea, but recently agreed to allow U.S. representatives to talk with Syrian officials at an international conference in Baghdad.
Pelosi's office said her trip was appropriate.
"The Iraq Study Group recommended a diplomatic effort that should include 'every country that has an interest in avoiding a chaotic Iraq," said deputy press secretary Drew Hamill. "This effort should certainly include Syria."
On other matters, Mr. Bush: