Sens. John McCain, R-Ariz., and Barack Obama, D-Ill., are already drawing up strategies for taking each other on in the general election, focusing on the same groups — including independent voters and Hispanics — and about a dozen states where they think the contest is likely to be decided this fall, campaign aides said.

Even before Obama fully wraps up the Democratic presidential nomination, he and McCain, the presumptive Republican nominee, are starting to assemble teams in the key battlegrounds, develop negative advertising and engage each other in earnest on the issues and a combustible mix of other topics, including age and patriotism.

McCain will spend this week delivering a series of speeches on global warming, evidence of his intention to battle Obama for independent voters, a group that both men have laid claim to.

Obama is likely to embark on a summertime tour intended to highlight the life story that was once central to his appeal. Preliminary plans include a stop in Hawaii, his birthplace.

Obama's campaign is firing up voter-registration efforts and sending campaign workers to Pennsylvania and Ohio, states that he lost in the primaries but that his aides said he must win to capture the White House.

McCain's advisers said they had tracked Obama's struggles with blue-collar voters there and would open campaign headquarters in both states in early June.

Beyond that, aides to both men said Hispanic voters would be central to victory in Southwestern states that are now viewed as prime battlefield states, including Colorado, Nevada and New Mexico.

McCain is looking first to states where President Bush narrowly lost in 2004 and where Obama lost primaries, starting with New Hampshire and Pennsylvania. Obama is looking to states where he won caucuses and primaries — including some, like Virginia, that have been solidly Republican in recent presidential elections — as well as others where he has organizations in place.

The Republican National Committee is planning a $19.5 million advertising campaign to portray Obama, 46, as out of touch with the country and too inexperienced to be commander in chief, seeking to put him on the defensive before he can use his financial advantage against McCain, 71, party officials said.

On the Democratic side, Obama's aides put finishing touches on advertisements intended to tether McCain to President Bush and chip away at his image as a maverick, an identity the aides said they found remained strong with voters.