US Senator John Kerry, the Democratic presidential candidate, said on Thursday that the stakes are high in the United States as the nation is at war on terror.

Depicting a gloomy picture in his acceptance speech at the party's national convention, Kerry said the American people were engaged in a global war against an enemy unlike any known before. Excerpts of his speech were released before its primetime delivery Thursday night.

"Here at home, wages are falling, health care costs are rising, and our great middle class is shrinking," he said.

Recalling the Clinton administrations in the 1990s, the Massachusetts senator said the Democratic governments balanced the budget and created 23 million new jobs, lifting millions out of poverty and the standard of living for the middle class.

The four-term senator also challenged President George W. Bush over Iraq. He said as president, he would immediately reform the intelligence system, "so policy is guided by facts, and facts are never distorted by politics," indirectly referring to the intelligence failures of the US intelligence community over Iraq's illicit weapons which Bush had used to justify the Iraq war.

He promised to make sure that the country "never goes to war because we want to, we only go to war because we have to."

Kerry vowed not to let any nation or international institution veto over issues on the country's national security. "I will never hesitate to use force when it is required," he said.

The United States needs a global effort against nuclear proliferation and a strong military, and needs to lead a "strong alliance," he said.

Kerry said the country's national security begins with homeland security, and pledged to implement recommendations made last week by the commission investigating the Sept. 11 attack if he was elected president.

The four-day convention would come to close Thursday night after Kerry's speech, the most important in his life which analysts said could define his ambitions for the White House.

Hours after his acceptance speech, Kerry and his vice presidential running mate John Edwards would set off on a coast-to-coast journey dubbed the "Believe in America Tour" to battleground states.