But a top Democrat questioned whether the American people have ever blessed the U.S.-led Iraqi reconstruction effort now under way.
"Is $87 billion a great deal of money?" Rumsfeld said before the Senate Appropriations Committee. "Yes. But can our country afford it? The answer is also yes. Because it is necessary for the security of our nation and the stability of the world."
Rumsfeld cited progress in reopening Iraqi schools and hospitals and training a new Iraqi army.
Rumsfeld and Gen. Richard Myers, the Joint Chiefs chairman, and Gen. John Abizaid, the head of U.S. Central Command, were appearing before the committee as the Bush administration continued its intensive push for approval of the $87 billion request.
At the same time, the U.S. civil administrator in Iraq, L. Paul Bremer, was making his third Capitol Hill appearance in three days, appearing before the Foreign Relations Committee. He was also going before the House Appropriations Committee on Wednesday afternoon and meeting with two other panels on Thursday.
Vice President Dick Cheney also met in a closed-door session with House Republican members. Lawmakers, said Republican Whip Roy Blunt of Missouri, gave Cheney a warm reception but also gave "notice to the vice president that we intend in the appropriations process to ask some tough questions."
Rep. Chris Cox, R-Calif., head of the Republican Policy Committee, said Cheney made clear that no U.S. money will be used to repay Saddam Hussein's debts to other countries.
Bremer and Rumsfeld's appearances at hearings come at a time when partisan fighting has increased over Iraq.
In a bristling exchange, Sen. Robert Byrd, D-W.Va., challenged Rumsfeld on the $20.3 billion part of Mr. Bush's plan that would go toward rebuilding Iraq and establishing a democratic government.
"Secretary Rumsfeld, where is the mandate from the American people to carry out the reconstruction of Iraq?" Byrd said. "When did the American people give their assent?"
Rumsfeld cited the resolution Congress approved allowing force against Iraq and defended rebuilding as being in U.S. interests.
"Once having gone in, the last thing we need to do is turn over that country to another dictator like Saddam Hussein," he said.
Underlining the partisan tensions over Iraq, when Byrd continued asking questions, committee chairman Ted Stevens, R-Ala., cut him off, saying Byrd had already exceeded his allotted time by seven minutes.
"Seven minutes," Byrd said. "Think of that, on an $87 billion request."
Bremer was appearing before a panel whose leaders had been urging the administration since before the war to lay out its strategy for rebuilding Iraq. Both Chairman Richard Lugar, R-Ind., and Sen. Joseph Biden, D-Del., have criticized the administration for failing to acknowledge the long-term costs and commitments involved.
"Many Iraqis have had a difficult time understanding how the most powerful nation in the world could defeat their armed forces in three weeks and still have trouble getting the lights turned on," Lugar said.
Biden said Mr. Bush's foreign policy "so poisoned the well" before the war by failing to build a broad international coalition, that next month's international donors conference is unlikely to generate more than $2 billion or $3 billion in support.
"It's a terrible indictment, in my view, of our foreign policy and a harsh example of the price of unilateralism," he said.
The action on Capitol Hill comes on the heels of Mr. Bush's speech to the United Nations, which got a cool reception from world leaders skeptical of U.S. reconstruction plans.
There was a time when Iraq was almost a nonpartisan issue in Congress. No longer. Sen. Ted Kennedy has called the war a fraud "made up in Texas," prompting a top Republican to accuse him of "hate speech." Bremer was said to have faced "a maelstrom" when he met with Democrats behind closed doors.
The mood is a striking change from last year when Mr. Bush was soaring in opinion polls, and Democrats were afraid to attack him on issues of national security. Opinion polls now show rising doubts about Mr. Bush's Iraq policies.
Many Democrats acknowledge that the $87 billion request likely will be approved because no one wants to oppose money for the troops. Daschle said Tuesday he doubts most senators will support the $20.3 billion part of the request that is for Iraqi reconstruction, but it's not clear that amount will be voted on separately.
Bremer received a harsh reception from Senate Democrats during a closed-door meeting with them Tuesday. When he began comparing the current situation to the German defeat in World War II, Sen. Jay Rockefeller, D-W.Va., asked him to discuss Iraq, not world history, according to one senator present.
"It was a maelstrom," said Sen. Tom Harkin, D-Iowa, who described the session.
Republicans are fighting back. Reacting to Kennedy's comments last week that the war was a fraud, House Majority Leader Tom Delay, R-Texas, said "Kennedy's brand of hate speech has become mainstream in the Democratic Party." Sen. Kay Bailey Hutchison of Texas said "sometimes I think, when I hear people talking, that they have forgotten that America was attacked."