Republicans heard the harshest attacks yet on Democratic presidential candidate John F. Kerry Wednesday night after President Bush arrived in the city where he will formally accept his party's nomination to run for a second term.

In an angry keynote speech on the third night of the Republican national convention at Madison Square Garden, Sen. Zell Miller of Georgia, a renegade Democrat who supports the reelection of Bush and Vice President Cheney, tore into Kerry and the Democratic Party, portraying them as weak on national security.

He was to be followed to the podium by Cheney, who, after an introduction by his wife, Lynne Cheney, also planned to denounce Kerry, peppering his address with the mocking barbs that have become a hallmark of his campaign appearances.

The speeches came after delegates formally renominated Cheney by acclamation. Bush, who flew in to New York after campaigning in Ohio, is scheduled to accept his nomination in a speech on the convention's closing night Thursday.

In his keynote speech, Miller, 72, who entered the Senate in 2000 after serving two terms as Georgia governor, repeatedly railed against the party that he has accused of increasingly alienating conservative Democrats like himself.

"Now, while young Americans are dying in the sands of Iraq and the mountains of Afghanistan, our nation is being torn apart and made weaker because of the Democrats' manic obsession to bring down our commander-in-chief," he said. "In their warped way of thinking, America is the problem, not the solution. They don't believe there is any real danger in the world except that which America brings upon itself through our clumsy and misguided foreign policy."

Listing a series of weapons systems that he said Kerry has opposed, Miller told the cheering delegates, "This is the man who wants to be the commander-in-chief of our U.S. Armed Forces? U.S. forces armed with what? Spitballs?"

Miller charged that Kerry "has made it clear that he would use military force only if approved by the United Nations. Kerry would let Paris decide when America needs defending. I want Bush to decide."

While Bush "wants to grab terrorists by the throat and not let them go," Miller said, "from John Kerry they get a 'yes-no-maybe' bowl of mush that can only encourage our enemies and confuse our friends."

He said he admired Bush because "he is unashamed of his belief that God is not indifferent to America."

Saying that Bush "is not a slick talker, but he is a straight shooter," Miller asserted, "Right now the world just cannot afford an indecisive America. Fainthearted self-indulgence will put at risk all we care about in this world.

In this hour of danger our president has had the courage to stand up. And this Democrat is proud to stand up with him."

After arriving in New York, Bush immediately headed to Queens to receive the endorsement of the Uniformed Firefighters Association of Greater New York, representing 20,000 active and retired firefighters.

The endorsement was symbolically important for Bush because firefighters played a heroic role in the city on Sept. 11, 2001, and thus helped to renew his association with the event that Republicans have made a centerpiece of their convention. In addition, the endorsement provides a bit of a counterweight to the strong union support for Kerry, who has won backing from the nation's largest firefighters union, the International Association of Fire Fighters.

Sounding the main themes of the convention's third day, Gov. Linda Lingle of Hawaii, the state's first woman governor and the first Republican to hold the office in 40 years, told the nearly 5,000 delegates and alternates that Bush's economic policies are working.

"President Bush pulled our nation's economy out of the recession he inherited and put us on the right track," she said. "The economy is strong and getting stronger."

The message was in keeping with what Republican Party leaders touted earlier as the advent of a period of "Bush prosperity" following what they said was a recession passed on to him by the Clinton administration. Democrats have said the economic turnaround happened in opposite fashion, with the Bush administration turning huge budget surpluses it inherited into record deficits.

While the convention's third day was meant to promote the United States as a "land of opportunity" as the gathering's overall theme, a number of speakers laced their addresses with caustic attacks on Kerry.

Massachusetts Gov. Mitt Romney blasted Kerry over what he described as vacillating positions on the war in Iraq. "He's campaigned against the war all year, but says he'd vote yes today," Romney said. "I don't want presidential leadership that comes in 57 varieties. I want a strong president who stands his ground. I want George W. Bush."

Rep. Paul Ryan of Wisconsin said, "During his 20 years in Washington, John Kerry never met a tax increase he didn't like. . . . John Kerry believes that government can spend our money better than we can. But most Americans don't share this view. That's why John Kerry has to preach the politics of division, of envy and resentment. That's why they talk so much about two Americas. But class warfare is not an economic policy. And the politics of division will not make America stronger, and it will not lead to prosperity. I say to them: Anger is not a governing philosophy."

Cheney also planned to draw a sharp contrast between Bush and Kerry, saying that America has reached one of its "defining moments," according to excerpts of his speech released by convention organizers.

"These have been years of achievement, and we are eager for the work ahead," Cheney said in one of the excerpts. "And in all that we do, we will never lose sight of the greatest challenge of our time: preserving the freedom and security of this nation against determined enemies."

In a campaign appearance in Tennessee Wednesday, Kerry charged that "extremism has gained momentum" under Bush as a result of a mismanaged war in Iraq.

"Today's terrorists have secured havens in Iraq that were not there before," Kerry told the national convention of the American Legion in Nashville. "And we have been forced to reach accommodation with those who have repeatedly attacked our troops."

Kerry criticized Bush's comment Monday that the war on terrorism may not be winnable, at least in a traditional sense. "With the right policies, this is a war we can win, this is a war we must win, and this is a war we will win," Kerry told the veterans group.

During a Republican youth convention on the floor of Madison Square Garden on the third day of the party's conclave here, several protesters briefly chanted slogans and held up signs against the Bush administration before they were dragged away kicking and screaming by convention security officers and Secret Service agents, Washington Post staff writer Ann Gerhart reported.

The protest broke out during a speech to the assembled youth by White House Chief of Staff Andrew H. Card Jr., who was introduced by Barbara and Jenna Bush, the twin daughters of President Bush and first lady Laura Bush.

Thousands of demonstrators have protested Bush policies outside the heavily secured, 18-square-block area surrounding Madison Square Garden, but protests inside the building are rare. Since late last week, more than 1,700 people have been arrested in convention-related protests in New York City, according to police, including nearly 1,200 on Tuesday.

As Card was speaking, half a dozen protesters jumped up on chairs and began shouting slogans such as "No more war" and waving signs demanding that Bush "stop AIDS" and reduce global debt. Some of the several hundred Bush supporters on the floor then drowned out the protesters with shouts of "Four more years" and held up their own placards to block those of the protesters.

One woman who witnessed the incident, Beth Price, 21, of Bowling Green, Ky., said punches were thrown. Secret Service agents yelled, "Make the hold!" as the protesters were seized. At least five -- two women and three men -- were forcibly removed, Gerhart reported.

In a separate demonstration Wednesday, thousands of people formed a symbolic unemployment line stretching from Wall Street to the convention site to protest Bush administration economic policies and job losses.

Previewing the daily theme of economic opportunity, Commerce Secretary Donald L. Evans and Republican governors contended that the economy -- a subject of attacks by the Kerry campaign -- now is stronger than it may appear.

"This president inherited a Clinton recession and turned it into the early stages of Bush prosperity," Evans said.

He added: "When you look at all of the economic data collectively, you can't do anything but conclude that this is a very strong economy, it continues to get stronger, it's a resilient recovery we have under way, we're in the early stages of Bush prosperity. But, yes, there's always more work to do, because you want to make sure that everybody in America that wants a job has a job. The president will talk about more work to do. He will talk about making the tax cuts permanent. He will talk about an ownership society."

Bush is scheduled to address the convention Thursday night when he formally accepts the nomination as the Republican presidential candidate in the Nov. 2 election.

Evans attacked the economic plan of Kerry, charging that the Massachusetts senator's vow to raise taxes on those making more than $200,000 a year would hurt small-business owners, who he said make up the "majority" of people in that tax bracket.

Kerry has said the tax increases for the wealthiest Americans would permit him to cut taxes for the middle class and that 98 percent of the people would pay lower taxes under his plan.

New York Gov. George E. Pataki, one of several governors appearing onstage at the news briefing, declared, "Quite simply, the president's economic policies are working."

He said a shaky economy at the outset of the Bush administration in early 2001 was dealt a severe blow by the Sept. 11, 2001, terrorist attacks.

"The terrorists are not believing that they can destroy us militarily," Pataki said. "They are looking to attack us economically and to make us weaker." He said Bush's tax cuts in 2001 "prevented what could have been an economic catastrophe given all of the conditions that he inherited and the attacks of September 11th."

Pataki seconded Evans's assessment, asserting, "President Bush inherited a recession. We are now seeing the beginning of Bush prosperity. And I'm confident that home ownership, job creation and economic strength will just get stronger under this president's leadership."

In advance of Cheney's speech, his wife Lynne and their daughter Elizabeth appeared on morning news shows to promote the Bush-Cheney ticket. On CNN, Elizabeth Cheney was asked about a comment in which Alan Keyes, a Republican candidate for senator in Illinois, called homosexuality "selfish hedonism" and said her openly lesbian sister, Mary Cheney, fit that description.

"I'm surprised, frankly, that you would even repeat the quote, and I'm not going to dignify it with a comment," Elizabeth Cheney said.

In an interview taped earlier and aired Wednesday on NBC's "Today" show, President Bush said Kerry's Vietnam War service, for which he won two medals for valor and three Purple Hearts, was "heroic . . . and he should be proud of it."

Bush also said that he was proud of his own service in the Texas Air National Guard during the Vietnam war.

Asked if "you think you both served on the same level of heroism," Bush replied: "No, I don't. I think his going to Vietnam was more heroic than my flying fighter jets. He was in harm's way. I wasn't. On the other hand, I served my country. Had my unit been called up, I would have gone."

Bush said he thought that "we ought to move beyond the past" and that "the real question is who best to lead us forward."

He said that in his convention speech Thursday night, "I'll say this is going to be a century of liberty. And I believe that. I believe it is our duty to lead the world."