President Bush arrived in New York last night as his running mate, Vice President Cheney, used his speech at the GOP convention to unleash some of the harshest attacks yet on the Democratic presidential nominee, Senator Kerry of Massachusetts.

Cheney described Mr. Kerry as a waffler who could not be trusted to be commander in chief.

“Senator Kerry’s liveliest disagreement is with himself. His back and forth reflects a habit of indecision, and sends a message of confusion. And it is all part of a pattern,” Mr. Cheney said. “Senator Kerry says he sees two Americas. It makes the whole thing mutual. America sees two John Kerrys.”

Mr. Cheney pointed to a series of issues on which Mr. Kerry has changed his views, including the war in Iraq, the North American Free Trade Agreement, and Mr. Bush’s education bill. The vice president said Mr. Kerry’s tendency to vacillate has done little harm thus far but could have a devastating impact if the senator becomes president.

“A senator can be wrong for 20 years, without consequence to the nation. But a president – a president always casts the deciding vote. And in this time of challenge, America needs and America has a president we can count on to get it right,” Mr. Cheney said. At several points, Mr. Cheney’s critique led delegates to erupt in a chant of “flip-flop, flip-flop.”

Mr. Cheney also said Mr. Kerry fails to appreciate the gravity of the threat to America’s security.

“Time and again Senator Kerry has made the wrong call on national security,” the vice president said. “Even in this post-9/11 period, Senator Kerry doesn’t appear to understand how the world has changed. He talks about leading a more sensitive war on terror, as though Al Qaeda will be impressed with our softer side.”

While Mr. Cheney drew cheers from the delegates, the crowd saved its most raucous reception for Senator Miller of Georgia, a Democrat who is supporting Mr. Bush. Mr. Miller lambasted Mr. Kerry, who he said had opposed nearly every major aircraft and weapons system used in the wars in Afghanistan and Iraq.

“This is the man who wants to be the commander in chief of our U.S. armed forces?” Mr. Miller asked. “U.S. forces armed with what, spitballs?”

The Georgia senator became the first convention speaker to take aim at Mr. Kerry’s actions as an anti-war protester after he returned from serving in the Navy in Vietnam.

“For more than 20 years, on every one of the great issues of freedom and security, John Kerry has been more wrong, more weak and more wobbly than any other national figure. As a war protester, Kerry blamed our military,” Mr. Miller said.

Mr. Miller suggested that if Mr. Kerry is elected, freedom itself would be at risk.

“This politician wants to be leader of the free world? Free for how long?” Mr. Miller asked.

Mr. Miller said Mr. Bush’s aggressive stance against terrorism has made Americans safer.

“George Bush wants to grab terrorists by the throat and not let them go to get a better grip,” Mr. Miller said. “From John Kerry, they get a ‘yes-no-maybe’ bowl of mush that can only encourage our enemies and confuse our friends.”

At least one of Mr. Miller’s assertions appeared to misstate Mr. Kerry’s current declared position.

“Senator Kerry has made it clear that he would use military force only if approved by the United Nations,” Mr. Miller said last night. “Kerry would let Paris decide when America needs defending. I want Bush to decide. John Kerry, who says he doesn’t like outsourcing, wants to outsource our national security.”

At the Democratic convention in July, Mr. Kerry said, “I will never hesitate to use force when it is required. Any attack will be met with a swift and certain response. I will never give any nation or international institution a veto over our national security.”

Mr. Miller said Mr. Kerry’s recent pronouncements should not be trusted. “Twenty years of votes can tell you much more about a man than twenty weeks of campaign rhetoric,” Mr. Miller said.

Democrats noted yesterday that Mr. Miller’s concerns about Mr. Kerry appear to have developed fairly recently.

At a Democratic Party dinner in Georgia in 2001, Mr. Miller called Mr. Kerry “one of this nation’s authentic heroes, one of this party’s best known and greatest leaders and a good friend.”

Last night, Mr. Miller expressed his disillusionment with his party for failing to give adequate support to Mr. Bush’s fight against terror.

“What has happened to the party I’ve spent my life working in?” Mr. Miller asked. “Today’s Democratic leaders see America as an occupier, not a liberator. And nothing makes this Marine madder than someone calling American troops occupiers rather than liberators.”

“Don’t waste your breath telling that to the leaders of my party today. In their warped way of thinking America is the problem, not the solution,” Mr. Miller said. “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.”

Like previous speakers, Mr. Cheney offered first-hand testimony aimed at countering perceptions that Mr. Bush has been cavalier in his decision-making.

“I have seen him face some of the hardest decisions that can come to the Oval Office and make those decisions with the wisdom and humility Americans expect in their president. George W. Bush is a man who speaks plainly and means what he says,” Mr. Cheney said.

Soon after Mr. Cheney began his remarks, a scuffle broke out between security personnel and a woman in a section reserved for alternate delegates. More than a dozen law enforcement agents converged on the woman and dragged her from the arena.

The distraction prompted Mr. Cheney to stop speaking for about a minute, as delegates chanted, “Four more years!”

Last night’s session was ostensibly devoted to Mr. Bush’s economic record. “A land of opportunity” was the catch phrase painted on signs around the hall. However, the night’s most prominent speakers clung to the national security themes that have dominated the gathering. Mr. Miller did not mention the economy at all and Mr. Cheney touched on the issue only in passing, saying, “The Bush tax cuts are working.”

Earlier in the night, Rep. Robert Portman of Ohio told delegates that the economy is bouncing back in his home state, which is expected to be a pivotal one in this fall’s election.

“This year we are adding jobs, including in manufacturing,” Mr. Portman said. “We’re on track for sustained economic growth.”

Another podium speaker, Senator Santorum of Pennsylvania, hailed Mr. Bush’s support for the use of federal funds to pay for religious counseling for couples who have had a child out of wedlock. Mr. Santorum faulted Mr. Kerry for opposing such programs on constitutional grounds.

“He says he’s concerned about the separation of church and state. Senator Kerry should worry more about the separation of children from their fathers,” Mr. Santorum said. “We all agree, religion in America must never be established, but it also must never be exiled.”

The roll call of states was completed last night. With no votes for any other candidates, Mr. Bush was officially nominated. The candidate arrived last night in Queens, where he ate pizza with members of a New York firefighters union that endorsed him.

Mr. Cheney was nominated by acclamation as the party’s vice presidential candidate.

As they have done previously, convention planners interrupted the proceedings last night for live television reports from various sites and for video presentations. A lengthy satirical video last evening was devoted to the premise that Mr. Bush’s dog, Barney, might become involved in the presidential campaign.

Mr. Bush’s political adviser, Karl Rove, and the White House chief of staff, Andrew Card, both had roles in the video, as did the White House press secretary, Scott McClellan. Mr. McClellan was shown moderating a debate between Barney and what appeared to be a French poodle, who was called “Fifi Kerry.”