The first Democratic delegates descended on their heavily fortified convention city Saturday as campaign officials said Sen. John Kerry's (search) main challenge was to persuade voters just tuning into the race to hand him the White House in an age of terrorism.

"It's very much a get-to-know-you process," said spokeswoman Stephanie Cutter (search) at the same time Kerry's convention scriptwriters labored to find the combination of words, symbols and images to make the perfect introduction.

Kerry, who runs even to slightly ahead of President Bush in pre-convention polls, campaigned slowly toward a convention city that has nurtured his career for decades.

"John Edwards (search) and I are determined that we are going to be champions for the middle class, the folks who built this country," he told an audience in Sioux City, Iowa, the state whose caucuses put him on the path to the nomination.

"We go to Boston, to the birthplace of the revolution of America and the possibilities of the future. And from there we go to the White House."

The convention is the country's first since the terrorist attacks of Sept. 11, 2001, and the security precautions showed it.

Air Force warplanes offered constant air cover for the city, and authorities said liquefied natural gas tankers which normally use Boston Harbor to reach their terminal would be denied access for the week.

The Coast Guard had infrared and night-vision cameras for use in its patrols of the harbor, while 100 video cameras silently scanned the area around the FleetCenter.

Inside the hall, the transformation from athletic arena to convention hall was nearly complete. A huge built-to-order podium filled one side of the facility, with 100,000 red, white and blue balloons nestled in the ceiling, to be dropped on cue.

For the delegates, the weekend promised a blur of pre-convention parties. Among them was a Sunday clambake for high-dollar Kerry donors, hosted by Massachusetts Sen. Edward M. Kennedy at the family compound on Cape Cod where John F. Kennedy sweated out the results of a close election more than four decades ago.

A dozen presidential campaigns later, another Massachusetts senator hopes to follow him to the White House.

Kerry, 60, arrives in Boston on Wednesday, although he isn't expected in the convention hall before he delivers his prime-time acceptance speech on the convention's final night.

Several officials said there were plans for Kerry to speak to the delegates by remote hookup on Tuesday night, when his wife Teresa takes her speaking turn at the convention podium. These officials spoke on condition of anonymity, noting the event has been designed as a surprise for Mrs. Kerry.

Kerry also is expected to attend a fireworks display on Wednesday night, a star-spangled spectacle timed to punctuate Edwards' vice presidential acceptance speech.

The political convention season opened with the electorate divided, Kerry having consolidated his support among Democrats and Bush among Republicans. Ralph Nader's inclusion in the surveys did little to change the outcome of the polls.

The latest Los Angeles Times survey showed Kerry and Bush in a statistical tie — 46 percent for the Democratic ticket and 44 for Bush and Vice President Dick Cheney. A Time Magazine survey released on the eve of the convention showed the race to be 48 percent for Kerry and 44 percent for Bush, with a 4 percent margin of error.

Many surveys also show that more than 50 percent of the electorate say they believe the country is on the wrong track — a clear indication that the nation may be ready to switch presidents.

But Kerry and his campaign agenda remain less known than Bush. In a Los Angeles Times poll, one-third of all voters said they didn't know enough about the four-term Massachusetts senator to form an opinion of him. A recent NBC/Wall Street Journal survey reported only 66 percent of voters knew a lot or a fair amount of what he stands for.

Campaign strategists said the millions of voters who don't know about Kerry comprise the audience they're targeting convention week.

Convention planners intend to present Kerry as a decorated Vietnam veteran, prosecutor and senator, and use his biography to depict him as a man who has served the country in a variety of ways.

Jim Rassman, who credits Kerry with saving his life in Vietnam decades ago, will speak to the convention Thursday night. Former Democratic Sen. Max Cleland of Georgia, a Vietnam veteran who lost three limbs on the battlefield, will deliver the formal introduction speech.

Campaign officials, who have the final say in virtually all of the dozens of speeches to be delivered over the four days, said they intend to devote little time to criticizing Bush from the podium.

The focus will be on Kerry and his agenda, said one strategist, who contended that there was no need to assail Bush because continuing violence in post-war Iraq and an economy still emerging from a slump was undercutting the president.

At the same time, Kerry's aides have taken pains to say they don't expect a major surge in public support as a result of the convention.

"Challengers sometimes get their convention and vice presidential selection bounces because they have not consolidated their partisan base," Kerry's pollster, Mark Mellman, wrote in a recent memo. This year, he said, "there is little base left for John Kerry to consolidate."

Bush, whose own nominating convention opens in New York in five weeks, was at his ranch in Texas. But his campaign did its best to depict Kerry as a lawmaker whose views are too liberal even for voters in his own, heavily Democratic state.