Republicans opened their party's national convention Monday with resounding endorsements of President Bush's leadership in the war on terrorism and repeated references to the Sept. 11, 2001, attack on the city's World Trade Center.

But the featured speakers of the convention's opening night at Madison Square Garden differed in their treatment of Bush's Democratic challenger, Sen. John F. Kerry of Massachusetts. While Sen. John McCain (R-Ariz.) reached out to Democrats in general and never mentioned Kerry by name, former New York mayor Rudolph W. Giuliani voiced sharp criticism of Kerry, describing him as weak, inconsistent and politically calculating.

Giuliani, a Republican who served as mayor at the time of the Sept. 11 attacks, spoke at length of that tragedy and Bush's response to it.

"For that and then his determined effort to defeat global terrorism, no matter what happens in this election, President George W. Bush has already earned a place in history as a great American president," Giuliani told cheering delegates. "But you and I, we're not going to wait for history to present the correct view of our president. Let us write our own history. We need George Bush now more than ever."

Giuliani went on to compare Bush to Winston Churchill, the British prime minister during World War II, and to the late president Ronald Reagan. And he quoted with approval Bush's dictum that in the war against the al Qaeda terrorist network of Osama bin Laden, "either you are with us or you are with the terrorists."

The former mayor said of Bush, "It doesn't matter to him how he's demonized. It doesn't matter to him what the media does to ridicule him or misinterpret him or defeat him. They ridiculed Winston Churchill. They belittled Ronald Reagan. But like President Bush, they were optimists; leaders need to be optimists. Their vision is beyond the present, and it's set on a future of real peace and security. Some call it stubbornness. I call it principled leadership."

Giuliani said, "One of my heroes, Winston Churchill, saw the dangers of Hitler while his opponents characterized him as a war-mongering gadfly. Another one of my heroes, Ronald Reagan, saw and described the Soviet Union as 'the evil empire' while world opinion accepted it as inevitable and even belittled Ronald Reagan's intelligence. President Bush sees world terrorism for the evil that it is. John Kerry has no such clear, precise and consistent vision."

Of the Democratic presidential nominee, Giuliani said, "John Kerry has made it the rule to change his position, rather than the exception. . . ." In contrast to Bush's policy of fighting terrorism "at the source," he said, "John Kerry's record of inconsistent positions on combating terrorism gives us no confidence that he'll pursue such a determined, difficult course."

In a preceding speech, McCain, a Republican maverick who has sparred with Bush and maintained a friendship with Kerry, appealed for national unity while endorsing Bush for a second presidential term.

McCain also staunchly defended his former political rival's handling of the war on terrorism and his decision to invade Iraq last year, deposing president Saddam Hussein.

But amid his generally conciliatory remarks, McCain drew thunderous applause when he delivered a sharp jab at Michael Moore, a filmmaker whose documentary, "Fahrenheit 9/11," excoriates Bush. He referred to Moore, who was in the conventional hall as an accredited columnist for USA Today, as "a disingenuous filmmaker who would have us believe that Saddam's Iraq was an oasis of peace when in fact it was a place of indescribable cruelty, torture chambers, mass graves and prisons that destroyed the lives of the small children held inside their walls."

As the audience hooted and chanted, "Four more years," the bearded Moore, wearing a baseball cap as is his custom, waved and mouthed, "Two more months," as he held up two fingers.

"I commend to my country the reelection of President Bush and the steady, experienced public-spirited man who serves as our vice president, Dick Cheney," McCain said to cheers from the audience.

"We need a leader with the experience to make the tough decisions and the resolve to stick with them, a leader who will keep us moving forward even if it is easier to rest," said McCain. "And this president will not rest until America is stronger and safer still. . . . He has been tested and has risen to the most important challenge of our time, and I salute him."

The speeches by McCain and Giuliani represented an effort by the Republicans to broaden their appeal among independents and Democrats in the midst of a convention largely dominated by GOP conservatives. Both McCain and Giuliani oppose some of the more socially conservative planks of the Republican Party platform that was adopted Monday, notably its call for a constitutional amendment that would ban gay marriage.

But McCain, who ran against Bush in the 2000 Republican presidential primaries, has said his disagreements with the Bush administration on that amendment and other issues -- including stem cell research, tax cuts and U.S. troop strength in Iraq -- are outweighed by the exigencies of fighting terrorism.

"Of course, we've disagreed on some specific issues and some important one," McCain said Monday on ABC's "Good Morning America" program. "But the overriding issue, the transcending issue, is the war on terror, and I believe that President Bush has proven himself the leader that we need for the next four years."

McCain, a former Navy pilot who spent five years as a prisoner of war in Vietnam after being shot down over Hanoi, has risen to the defense of Kerry, a fellow senator and Vietnam veteran, in the face of attacks questioning actions that won him medals for valor and three Purple Hearts. McCain has been especially sensitive about such attacks because of his own experience while running in the South Carolina primary four years ago, when a veterans group supporting Bush attacked McCain's record on veterans issues and accused him of abandoning veterans after he came home from Vietnam.

Bush, who declined to either endorse or reject that characterization of McCain, also has refused to repudiate the attacks on Kerry by a group called Swift Boat Veterans for Truth. McCain has called those attacks "dishonest and dishonorable," a phrase he repeated Monday, and has urged Bush to publicly denounce them. However, McCain said on morning news programs that Kerry's antiwar activities after returning from Vietnam three decades ago were fair game for criticism in the current political campaign.

In his speech Monday night, McCain recalled the unity that the nation experienced in the wake of the Sept. 11 attacks.

"We must, whatever our disagreements, stick together in this great challenge of our time," he said. "My friends in the Democratic Party, and I'm fortunate to call many of them my friends, assure us they share the conviction that winning the war against terrorism is our government's most important obligation. . . . I don't doubt the sincerity of my Democratic friends. And they should not doubt ours."

McCain added: "We have nothing to fear from each other. We are arguing over the means to better secure our freedom, and promote the general welfare. But it should remain an argument among friends who share an unshaken belief in our great cause, and in the goodness of each other. We are Americans first, Americans last, Americans always. Let us argue our differences. But remember we are not enemies, but comrades in a war against a real enemy. . . ."

While McCain shunned any personal criticism of Kerry, earlier speakers sounded themes similar to Giuliani's as they denounced the Democrat while repeatedly invoking the attack on the World Trade Center about four miles south of the convention site.

While Bush "shares the hopeful vision" of presidents Abraham Lincoln and Ronald Reagan, Kerry "is on the wrong side" of today's major issues, said the convention chairman, House Speaker J. Dennis Hastert of Illinois, in an evening speech to the gathering.

The Massachusetts senator "is on the wrong side of taxation, of litigation and of regulation," and he has wavered on the war in Iraq, Hastert said. He added: "John Kerry wants to throw the taxpayers overboard. Both President Lincoln and President Reagan understood that in order to be respected around the world, you have to have the courage to stand up for America. George Bush shares the Lincoln and Reagan vision. . . .

"My friends, this is no time to pick a leader who is weak on the war and wrong on taxes. George W. Bush is a strong leader with the right vision for America."

Hastert delivered the endorsement after the convention's evening session opened with an introductory video in the style of the "Saturday Night Live" comedy program, complete with an announcer intoning the names of the featured dignitaries over the blare of a saxophone. Later, former president George H.W. Bush, father of the incumbent, was introduced as a Van Halen rock song, "Jump," played over the site's sound system.

Throughout the convention's opening day, organizers sought to portray the GOP as open to youth and minorities. Hispanics and blacks were featured prominently, and one of the evening speakers was a Muslim woman wearing a headscarf.

Among the speakers were widows of Sept. 11 victims. The convention was also shown of firefighters, who praised Bush's leadership on the day of the attacks.

"We've shown the world that New York can never be defeated," said the city's Republican mayor, Michael R. Bloomberg, in one of the opening speeches after the convention was gaveled to order Monday morning. He said Bush's choice of New York to host the GOP's nominating convention for the first time "was a show of faith that required courage and vision and one that all New Yorkers will not forget."

The names of Bush and Vice President Cheney were formally placed in nomination as the Republican candidates to run for reelection against Kerry and Democratic vice presidential nominee John Edwards in the Nov. 2 election. Bush, who campaigned in New Hampshire and Michigan on Monday, is scheduled to formally accept the nomination in a speech Thursday night.

Bush's name was placed in nomination by Juan Jose Perez, a Hispanic delegate from the battleground state of Ohio, who hailed Bush as "a strong and compassionate leader." The assembled Republicans, among the nearly 5,000 delegates and alternates in attendance, then erupted in cheers and chanted, "Four more years."

Cheney's name was subsequently placed in nomination by a delegate from his home state of Wyoming. With his wife, Lynne Cheney, by his side, the vice president rose from his seat on the convention floor and waved to acknowledge the applause.

In an interview on NBC's "Today" show, Bush said the first four years of his presidency have been "defined by 9/11" and cautioned that the war on terrorism, specifically against the al Qaeda network of Osama bin Laden, will continue indefinitely.

"I don't think you can win it," he said. "But I think you can create conditions so that those who use terror as a tool are less acceptable in parts of the world."

He said he has "a two-pronged strategy" to preempt future attacks by staying on the offensive in the near term and to "spread freedom and liberty" around the world in the long term.

"The country must never yield, must never show weakness, must continue to lead to find the al Qaeda affiliates who are hiding around the world and who want to harm us, and bring them to justice," Bush said.

Edwards criticized Bush for his remarks Monday, asserting that the Democrats have a better plan to make the country safer.

"After months of listening to the Republicans base their campaign on their singular ability to win the war on terror, the president now says we can't win the war on terrorism," Edwards said in a statement issued in Wilmington, N.C. "This is no time to declare defeat -- it won't be easy and it won't be quick, but we have a comprehensive long-term plan to make America safer. And that's a difference."

As a result of the Sept. 11 attack on New York, Bloomberg told the convention's opening session, "our knees buckled, but we stayed on our feet, and we showed that our dreams, like our liberties, will never be lost to violence or hate." He said the city "remains in the front lines in the war on terror" and that Bush "deserves our support" in leading that war.

Some Sept. 11 survivors and family members have charged that the Republicans were exploiting the tragedy for political gain by holding their convention here, and the party has said publicly that the city was chosen last year because it offered "the best package of goods and services" for the convention, including hotels, the Madison Square Garden complex, other venues and event funding.

But speakers Monday abandoned any defensiveness about Sept. 11, portraying the convention here as a vote of confidence in New York City and a defiant response to the terrorists who have targeted it.

Former New York police commissioner Bernard B. Kerik, who headed the 41,000-member uniformed force at the time of the attack, suggested that the GOP's choice of the venue headed off a move by the Democrats to hold their own nominating convention here.

"If the Republicans didn't come to New York, the Democrats were thinking about coming to New York," he told a press briefing.

"I personally think this is a special place for the convention to be with regard to 9/11," he said, adding, "You can't say 9/11 didn't happen."

Kerik, who served as a senior adviser in Iraq for four months last year, said Bush had shown his mettle by coming to New York and standing at the site of the collapsed World Trade Center towers three days after the attack. He said he was concerned at the time about follow-up attacks and the air quality, among other things, and that he had not wanted Bush to come.

"I'd say the president had enormous courage in coming to New York on Sept. 14," Kerik said.

Kerik said New York City remains under "an imminent threat" of attack by terrorists, but he asserted that America is safer today than it was three years ago as a result of Bush's policies.

Asked how declarations of a safer country could be reconciled with the unprecedented security for this week's convention here, Kerik said, "I don't think this is a contradiction; I think it's a reality." He said al Qaeda wants to carry out an attack that would affect the U.S. presidential election, and that the government is determined to prevent that.

"They're not going to influence this election like they did in Spain," Kerik said, referring to the victory of Spain's opposition Socialist Party three days after the bombing of commuter trains in Madrid on March 11.