Sen. John F. Kerry (Mass.) has begun targeting swing voters and disaffected Republicans in an effort to expand the election battleground, a strategy that includes emphasizing centrist themes on the campaign trail while privately reassuring liberal constituencies he is committed to their core issues.

After watching and sometimes wincing at a clip of himself on the evening news in California earlier this month, Kerry has tried to adjust his campaign pitch by toning down the rhetoric and dropping some of his more bombastic sound bites from the primary campaign. His stump speech now includes a measured appeal to independents and "non-Bush Republicans" and the assertion that he is more conservative than the president when it comes to budget deficits and respecting the Constitution.

Kerry aides have been talking about investing money for advertising in additional Republican-leaning southern states, including North Carolina and possibly Virginia, that most analysts consider strong Bush country. Kerry is also intrigued with the idea of putting an unmistakable bipartisan stamp on his candidacy by appearing to woo a Republican such as Sen. John McCain (Ariz.) as his running mate, or at least signaling his intention to tap Republicans for key Cabinet posts, according to some aides.

Sen. Chuck Hagel (R-Neb.) said four Democrats not part of the Kerry campaign have asked whether he has any interest in joining Kerry's ticket. Hagel said no, but, in an interview Friday, applauded Kerry's interest in creating a bipartisan government. McCain, too, has repeatedly ruled out becoming Kerry's running mate, though the two share a dislike for the Bush administration. Kerry will name his choice for vice president in July, according to a Democrat familiar with the selection process.

Kerry's effort to adjust his message also represents a strategic necessity for another reason. A top Democratic strategist, who discussed private data on the condition of anonymity, said internal polling shows that Kerry is still viewed as a Massachusetts liberal by a large number of independents and some Republicans who express a willingness to vote for a Democrat.

Several party officials said the candidate's close affiliation with Sen. Edward M. Kennedy (Mass.), one of the country's best known liberals and war critics, is hurting Kerry's standing in the middle. Kennedy's prominence at the Democratic National Convention in Boston in July could reinforce that connection.

Kerry advisers talk openly about expanding the electoral map and appealing to swing voters and even some Republicans. This is "our target audience," Tad Devine, a top Kerry adviser, told reporters last week at a breakfast hosted by the Christian Science Monitor. "It is our intention to expand the race further into red states."

Devine was referring to the states Bush won in 2000, which are generally colored red in contrast to the Democrats' blue on most political maps. He said the campaign would like to put as many as 380 electoral votes into play by moving more aggressively into the South, although several Democrats said this would be a waste of time and money.

The campaign recently launched television ads in Louisiana and Colorado, both of which Bush won in 2000, forcing the president's campaign to shift gears and follow the Democrat on the air in both states.

Bush strategists say Kerry will meet resistance if he tries to expand the electoral map beyond the states where the Democrat is currently advertising. "Realistically, I don't think there's any place [else] they could" compete, said a senior Bush adviser. "And I don't think Louisiana is realistic." Even Colorado, he predicted, will be in Bush's column in November, although he conceded it might be competitive.

Both campaigns are spending heavily on organizational efforts designed to maximize turnout among their partisans, but advisers to Bush and Kerry have concluded that attracting the relatively small pool of undecided voters is essential.

Kerry hopes to appeal to them by softening his liberal image in the coming months, and his stump speech now includes passages designed to suggest he is reaching across party lines to voters disaffected with the president.

At a fundraiser at the Connecticut home of singers Paul Simon and Edie Brickell on Friday night, Kerry put it this way: "This race is not primarily about party, it's not about labels. Discard 'Republican,' 'Democrat,' 'liberal,' 'conservative.' It's about common sense, mainstream American values and how we make our country stronger."

Whether Kerry can authentically project a more moderate message is a major question. He has one of the most liberal voting records in the Senate, but centrist Democrats say that on many defining votes in the 1990s -- welfare reform and free trade among them -- Kerry sided with the centrist wing of the party against the liberal wing.

Bruce Reed, president of the Democratic Leadership Council, called Kerry "a reform Democrat his whole career," and argued that Kerry has been identified as a liberal largely because he comes from Massachusetts. "It's more a question of geography than philosophy or ideology," he said.

Still, as Kerry seeks to broaden his message, he is mindful of not offending his base, although his task may be easier than the tasks of some nominees in the past because of the desire among Democrats of all stripes to defeat Bush.

"Bush organizes the base for Kerry in the way that Clinton organized the right for Republicans," said Robert L. Borosage of the liberal Campaign for America's Future. He added: "There is a lot of space for Kerry to find his own voice without having to worry about massive disaffection" on the left.

David Axelrod, a Democratic media consultant, said that "hardcore Democrats are so invested in defeating Bush" that Kerry has the "latitude to do whatever he needs to do."

Some Democrats argue that Kerry's sometimes-nuanced policy positions may prove to be an asset in mollifying the left as he reaches for the center. Republicans, who have been quick to exploit any Kerry statement that appears to conflict with a previously held position in efforts to portray him as a politician with few firm convictions, scoff at that idea.

Despite the unity among Democrats, Kerry is working feverishly to placate liberals who might feel slighted by his new approach. At a recent private meeting, the Massachusetts senator assured gay rights activists that his public silence on the gay marriage debate does not reflect his strong, personal commitment to their issues, participants said.

Kerry advisers said a strong public defense of gay marriage could undermine the candidate's appeal in culturally conservative states, so he rarely raises it on the hustings. Last week, after speaking in Topeka, Kan., at a ceremony marking the 50th anniversary of the Supreme Court's school desegregation decision in Brown v. Board of Education, he was asked why he did not mention gay marriage, since that day also marked the first day his home state was allowing such unions. He brushed aside the questions without answering.

Kerry has also come under fire among African Americans after some black lawmakers raised concerns about the prominence of minorities and minority issues in his campaign. Kerry aides promised to promptly deliver to black lawmakers details of a new paid media campaign in urban areas, and the campaign quickly hired several minority staffers.

"It's not enough to go out and just have a centrist message," said Rep. Elijah E. Cummings (D-Md.), chairman of the Congressional Black Caucus. "He can be there presenting his centrist message and at the same time, he has to address African Americans and their issues." However, "where we have differences, we have to punch it out behind closed doors," he said.

Still, Cummings said his group is so pleased with Kerry's overtures it will soon endorse the candidate and take his message to black communities.

While Kerry often portrays himself as a Bill Clinton Democrat in public, he seemed to distance himself from the former centrist president during a private meeting last week with independent presidential candidate Ralph Nader, who is challenging the presumptive Democratic nominee from the left flank and who complained that the party has sold out to corporate interests.

" 'Don't judge me by the people who preceded me,' " Kerry told Nader, according to a Kerry aide who briefed reporters on the condition of anonymity. " 'You may have had a disagreement with Bill Clinton, or Al Gore, or the Democratic leadership in Congress . . . but that's not me. I have fought with you, I have been with you on a range of issues.' "

Earlier this year, Kerry told audiences that on economic policy, he would follow in Clinton's tradition: "If you liked what Bill Clinton gave you in eight years, you'll love what John Kerry will give you in the first four."

What is more remarkable to many Democrats is how Kerry is catching little flak from the party's base even when he strays from liberal orthodoxy. Abortion rights groups, for example, defended Kerry this past week when he told the Associated Press he would consider nominating antiabortion judges. Even so, Kerry sent a clear message to the base hours later when he issued a statement saying he would never appoint an abortion rights opponent to the Supreme Court.

Rep. Jim McDermott (D-Wash.), a liberal who supported former Vermont governor Howard Dean for the nomination, said most Democrats are turning a blind eye to the candidate's centrist positions, such as an across-the-board tax cut for U.S. corporations. He called the plan little more than "campaign rhetoric."

"That's not going to get me upset," he said. "The basic thing here is you won't see people getting bent out of shape about anything going on in the moment."

The only thing that could turn liberal Democrats against Kerry would be a dramatic turn for the worse for Kerry in polls, several Democrats said.