Sens. John McCain and Barack Obama are already drawing up strategies for taking each other on in the general election. They're focusing on the same groups -- including independent voters and Latinos -- 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 the next week delivering a series of speeches on global warming, evidence of his intention to battle Obama for independent voters, a group both men have laid claim to. The rivals could even stage joint forums this year -- unprecedented in a presidential race -- in an idea floated by McCain's advisers. On Saturday, Obama called the proposal "a great idea."

Clearly concerned that questions about such things as his association with his former pastor have damaged his standing with independents, 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, and a major address there at the National Memorial Cemetery of the Pacific, in Punchbowl Crater, where his maternal grandfather, who fought in World War II, is buried.

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.

The decisions by McCain and Obama to look ahead to the fall reflect their conclusion that it is only a matter of time before New York Sen. Hillary Rodham Clinton steps away from the fight for the Democratic nomination.

McCain, an Arizona senator, is looking first to states where President Bush narrowly lost in 2004 and where Obama lost primaries, starting with New Hampshire and Pennsylvania. Obama, an Illinois senator, is looking to states where he won caucuses and primaries -- including some, like Virginia, that have been solidly Republican in recent presidential elections.

And both sides have produced TV advertisements that will be rolled out as soon as the Democratic contest is officially resolved. These advertisements are directed less at promoting themselves than at undercutting their opponents.

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.

"In 1984, Ronald Reagan said, 'I'm not going to exploit for political purposes my opponent's youth and inexperience,' " said Frank Donatelli, the deputy chairman of the Republican National Committee. "Well, we are going to exploit Obama's youth and inexperience."

On the Democratic side, Obama's aides this week 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.

"By November, every voter will know that McCain is offering a third Bush term," said David Plouffe, Obama's campaign manager.

The strategies reflect a lesson from the 2004 presidential campaign, when top aides to Bush, some of whom are working for McCain today, began a well-financed television campaign to define and undercut Sen. John Kerry, D-Mass., the moment he became his party's nominee.

Both sides say the states clearly in play now include Colorado, Florida, Iowa, Michigan, Minnesota, New Hampshire, New Mexico, Nevada, Ohio, Oregon, Pennsylvania, Virginia, Washington and Wisconsin.

Republicans said they hoped to put New Jersey and possibly California into play; Democrats said blacks could make Obama competitive in Georgia, North Carolina and South Carolina.

Obama's advisers said they had a strong chance of taking Colorado, Iowa, Nevada, New Mexico, Ohio and Virginia away from the Republican column.