Senator John Kerry formally accepted the Democratic Party's nomination for president, calling the upcoming election the most important in a lifetime. The senator's remarks came on the closing night of the Democratic National Convention.

Delegates on the convention floor here in Boston erupted in applause as Senator Kerry arrived on stage to give what most political analysts called the most important speech of his life.

The senator from Massachusetts quickly framed the November presidential election as one of extraordinary significance.

"This is the most important election of our lifetime. The stakes are high. We are a nation at war -- a global war on terror against an enemy unlike any we have ever known before. And here at home, wages are falling, health care costs are rising, and our great middle class is shrinking," he said.

Before this convention began, Mr. Kerry's advisors said their goals were to reintroduce the candidate to American voters while emphasizing his national security credentials and military experience as a war hero in Vietnam.

In his speech the Democratic candidate said after years working with national security issues as a U.S. senator, he is ready to be Commander in Chief.

"Let there be no mistake: I will never hesitate to use force when it is required," he said. "Any attack will be met with a swift and certain response. I will never give any nation or any institution a veto over our national security. And I will build a stronger American military."

Mr. Kerry says as president he will improve America's intelligence system and protect it from political influence.

The senator says he will immediately implement the recent recommendations of the commission investigating the September 11th, 2001 terrorist attacks on the United States.

"I will immediately reform the intelligence system, so policy is guided by facts, and facts are never distorted by politics," he said. "And as president, I will bring back this nation's time-honored tradition: the United States of America never goes to war because we want to, we only go to war because we have to."

Senator Kerry then made an unusually open appeal to his opponent in the general election, President Bush. "I want to address these next words directly to President George W. Bush: In the weeks ahead, let's be optimists, not just opponents," he said. "Let's build unity in the American family, not angry division. Let's honor this nation's diversity; let's respect one another; and let's never misuse for political purposes the most precious document in American history, the Constitution of the United States."

Mr. Kerry said Democrats are optimists and what he called "can do people."

He listed the economic gains made during the eight years when former President Bill Clinton was in office and said such progress can made again.

"For all those who believe our best days are ahead of us with great faith in the American people, I accept your nomination for President of the United States," he said.

The convention ended as 100,000 red, white and blue balloons fell from the ceiling and the Democratic delegates celebrated what has been a unified gathering.

Democrats hope four days in the spotlight will provide a measurable surge in public opinion, known as "bounce," which in the past has given nominees a boost in the popularity polls. The Republicans will expect a similar "bounce" after nominating President Bush at their party's convention late next month in New York City.

Political analysts say, however, that because of a closely divided electorate and a relatively small number of undecided voters, a huge bounce is unlikely this year.

Senator Kerry and Vice Presidential nominee John Edwards will spend the next two weeks campaigning across America, visiting battleground states considered critical to victory in the November election.