-- Sen. John F. Kerry campaigned through the battleground state of Ohio on Sunday and paid a surprise visit to Fenway Park here on Sunday night as Democrats prepared for the opening day of a national convention that party officials vowed would accentuate the positive and tone down attacks on President Bush.

Amid protesters and unprecedented security preparations that turned the area around Boston's FleetCenter into an armed encampment, the Democrats will gavel the convention to order at 4 p.m. on Monday, and are set to turn the opening night spotlight on former presidents Jimmy Carter and Bill Clinton and former vice president Al Gore.

Clinton will help remind voters of the economic prosperity of the 1990s. Gore, by his very presence, will reinforce for party activists the bitter memories of a 2000 election defeat that have helped to motivate Democrats throughout the campaign.

The rest of the week will mix such Democratic luminaries as Sen. Edward M. Kennedy (Mass.) with some of the party's rising stars and with ordinary Americans from across the country. All will have the assignment of not only giving voters a fuller portrait of Kerry but also highlighting the stakes of a fiercely contested election. Sen. John Edwards (N.C.), Kerry's running mate, will take center stage on Wednesday night. Kerry's heavily anticipated acceptance speech, in which he will seek to give voters a sense of his vision and also his character and convictions, will be the culminating event Thursday night.

A senior campaign official said on Sunday that Kerry will lay out a vision for the country and will attempt to give voters a more complete, personal picture of a candidate whom many say they still don't know.

"Most [Americans] have seen little pieces here and there. . . . This will be the first time they have had any period of long exposure" to the candidates, the official said.

The address Edwards delivers Wednesday night will speak to the nation's middle class, and is to make reference to the "two Americas" stump speech -- about the haves and have-nots -- that dominated his campaign during the primaries. The official said that Edwards has written the speech longhand on legal pads.

Arriving delegates planned to party late into Sunday night, with a ticket for the Red Sox-Yankees game at Fenway Park the most coveted in town. But on Monday they will get down to business. Democratic National Committee Chairman Terence R. McAuliffe said that, in addition to attending the speeches and events in FleetCenter each evening, delegates will be expected to participate in daily training sessions to prepare for voter mobilization efforts for the fall campaign.

That sense of purpose pervades the convention as the Democrats seek to capitalize on their unusual unity. Disputes, large or small, that have colored previous Democratic conventions are largely absent, and Kerry officials hope that the singular focus on turning Kerry into a more appealing candidate will produce political dividends when he and Edwards return to the campaign trail.

Anger at Bush has fueled Democrats throughout the presidential campaign, stoked initially by former Vermont governor Howard Dean and his opposition to the Iraq war. The other Democratic candidates, including Kerry, quickly appropriated portions of Dean's angry, anti-Bush message, but advisers have pushed Kerry in recent weeks toward a more forward-looking message and away from Bush-bashing.

Kerry strategists see the convention as an opportunity to reach out to voters who have paid only sporadic attention to the campaign and who, they believe, are more interested in hearing what Kerry would do as president than a harsh Democratic critique of Bush's presidency.

"This is more a convention for introducing John Kerry to people who don't know him," Michigan Gov. Jennifer M. Granholm told Washington Post editors and reporters Sunday afternoon. "That's why you're not going to hear the partisan rhetoric you've heard [at past conventions]. . . . This is about persuasion. It's not about rallying the troops."

But in a campaign in which both parties have spent tens of millions of dollars on negative ads, there are limits to the Democrats' desire to put on a cheerful face. "You will hear about George Bush," Kerry communications director Stephanie Cutter said. "His name will come up. This is a political convention."

Cutter said the main objective for the week will be to fill out the "stronger at home, respected in the world" convention theme. "We are filling out what those words mean in terms of a John Kerry-John Edwards presidency," Cutter said. "We are driving a message every day. Bush will come up; mark my word. But we don't feel we have to spend any real time talking about George Bush because it's his record that impacts the daily lives of the American people."

Party leaders and convention speakers filled the Sunday talk shows promoting Kerry's candidacy and fending off criticism from Republicans. Kennedy, appearing on ABC's "This Week," said GOP efforts to label Kerry as a liberal and tie him to Kennedy's liberal record will have little effect on voters.

Kennedy, one of the most vocal opponents of the war in Iraq, defended Kerry's vote in support of the war but asserted that Kerry would have pursued a different course than Bush. "We never would have gone to war," he said.

Kerry spent Sunday morning at First Church of God in Columbus, Ohio, where he told the largely black congregation that he had come "not to speechify but to worship and to praise." Later he spoke to citizens in Ward 62, which Bush carried by 12 votes in 2000.

Kerry then diverted from his planned schedule for a detour to Boston, where he threw out the first pitch at the Red Sox-Yankees game. Kerry was greeted with cheers and boos when he was introduced to the crowd, and that chorus accompanied him as he went onto the field and as he departed.

Edwards campaigned in San Antonio, where he promoted the day's message of opportunity at a Youth Build site where at-risk youth learn trades and earn high school diplomas.

Sitting in his white shirtsleeves at a construction site, Edwards questioned about a dozen high school students about what they have learned from the program. The forum was set up in the sweltering heat, on the concrete slab of a new, massive gymnasium the students are helping build.

"My favorite thing is the demolition work. I like to tear down the walls and straighten things out," Torien Lyons, 16, said to much laughter.

Edwards was encouraging and comforting to the students, some of whom seemed quite nervous speaking about their newfound confidence in front of the media and observers at the public event. "Hard work won't hurt you," Edwards told the students, comparing his own experiences as a youth. "It will help make you better."

Edwards also raised $600,000 for the campaign and the party, as the Kerry-Edwards campaign announced that he was giving back $44,000 raised for his own presidential campaign by Pierce O'Donnell, a prominent Los Angeles entertainment lawyer who is under investigation for questionable fundraising in the Los Angeles mayor's race. Newsweek first reported on the investigation.

Edwards spokesman Mark Kornblau said that although none of O'Donnell's contributions to Edward have come under scrutiny, the campaign opted to "go above and beyond" what is required to keep the campaign focused on issues.

Staff writers Jim VandeHei, traveling with Kerry, and Lois Romano, traveling with Edwards, contributed to this report.

Democratic candidate John F. Kerry, with wife Teresa Heinz Kerry, waves to the crowd at the Yankees-Red Sox game in Boston. Kerry threw out the first pitch.