President George W. Bush predicted in an interview broadcast today that the fight against terrorism, which has been a centerpiece of his presidency, will be won within the next generation, if the United States remains resolutely on the course he has charted for the country.

"When we succeed in Iraq and Afghanistan it’s the beginning of the end for extremists," he told NBC television in an interview. "I think if we are strong and resolute, it’s less likely that your kids will live under the threat of al-Qaeda for a long period of time.

"I don’t have a definite end," the president continued on the eve of his nomination to a second four-year presidential term at the Republican National Convention in New York City this week. "But I want to make sure your kids can grow up in a peaceful world. If we believe you can’t win, the alternative is to retreat.

"We cannot show weakness in this world today, because the enemy will exploit that weakness," Mr Bush continued. "It will embolden them, and make the world a more dangerous place."

Mr Bush takes the stage at New York’s Madison Square Garden on Thursday to accept the nomination for president, starting the final phase of a campaign which he hopes will return him to the White House when voters go to the polls on November 2.

Mr Bush planned to campaign today in New Hampshire, which has voted for only four Democratic presidential nominees in the past 100 years but is up for grabs this November. It’s his eighth trip to the state as president. Four years ago, he won New Hampshire by 7,211 votes, or just a little more than 1 percentage point. While Republicans outnumber Democrats among the state’s registered voters, more than a third of those registered are independent.

The 58-year-old Texan has made the war on terror the centrepiece of his re-election bid, but Republicans got a taste of popular anger over Iraq as demonstrators staged a massive anti-Bush rally here on Sunday.

Defying a sweltering late-summer sun, more than 100,000 protesters flooded the streets of New York for a noisy but peaceful protest that attracted war veterans, grandmothers, ageing hippies and fed-up Americans of all stripes.

New York police said they arrested 200 people, mostly for disorderly conduct and away from the march itself. There were no major incidents or injuries, police commissioner Raymond Kelly said.

The demonstrators marched in front of Madison Square Garden, the famed New York sports arena where the convention will kick off on Monday morning amid an unprecedented security lockdown. SWAT teams in all-black riot gear, secret service agents, New York police and other security personnel have turned the normally bustling area into a virtual fortress.

A high-tech intelligence analysis centre with staff drawn from 20 agencies opened in New York last week to guard against the possibility of terrorist attacks during the convention. The Bush administration has said it has intelligence that al-Qaeda may want to strike again before the election, and many New Yorkers have been angered that the Republicans chose to hold their convention in the city.

Bush critics have accused the Republicans of trying to mask the party’s true values by scheduling prime-time speakers such as Arnold Schwarzenegger and Rudolph Giulani, whose moderate policies sometimes clash with those of the president. The keynote address of the convention is being given by a Democrat, Senator Zell Miller.

One of the highlights on Monday’s opening night is a speech by John McCain, a maverick Arizona senator whose character was rubbished in the 2000 Republican primaries and who had flirted with Democratic hopeful John Kerry. According to advance copy of his speech, Mr McCain will laud the president’s campaign against terrorism. "He has been tested and has risen to the most important challenge of our time, and I salute him. I salute his determination to make this world a better, safer, freer place," McCain will say.

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