Obama scored three decisive victories in the Potomac Primaries, winning handily in Maryland, Virginia and the District of Columbia.
"The change we seek swept through the Chesapeake and over the Potomac ... And although we won in D.C., this campaign won't be over until there is change in Washington, D.C.," Obama told thousands of supporters in Wisconsin, a state that votes on Feb. 19.
In a noted shift in his campaign rhetoric, Obama largely ignored Clinton, only obliquely referring to statements from her campaign that accused him of peddling false hope.
"The cynics can no longer say our hope is false," Obama said.
Instead, Obama focused on his appeal among a broad swath of the electorate.
"We are bringing together Democrats and independents and even Republicans," Obama told a raucous crowd in Madison, Wis., "'Obamicans,' we call them. They whisper to me and they say, 'I am a Republican, but I support you', and I say back, 'Thank you.'"
But beyond his appeal to groups outside of traditional Democratic voters, Obama took aim at the leading Republican candidate, pointedly referring to "Bush-McCain Republicans" that "send troops to fight in Iraq tour after tour."
"George Bush won't be on the ballot this November," Obama said to loud cheers. "My cousin Dick Cheney won't be on this ballot, but the Bush-Cheney war and the Bush-Cheney tax cuts will be on the ballot."
Obama's speech sharpened the campaign's focus on McCain, taking direct aim at the Arizona senator's support for the troop surge in Iraq and tax cuts passed during the early days of the Bush administration.
His speech, and the noted absence of material addressing his Democratic opponent, highlighted the growing confidence of the Obama camp as it racked up consecutive wins Nos. 6, 7 and 8 by wide margins on Tuesday.
During a victory speech in Alexandria, Va., McCain took a swipe at Obama's message of hope.
"My hope for our country resides in my faith in the American character, the character which proudly defends the right to think and do for ourselves, but perceives self-interest in accord with a kinship of ideals, which, when called upon, Americans will defend with their very lives," he said.
"To encourage a country with only rhetoric rather than sound and proven ideas that trust in the strength and courage of free people is not a promise of hope," McCain continued. "It is a platitude."
Obama won most demographic groups in voting in Maryland and Virginia, according to Associated Press exit polls.
But the Clinton camp, seeking to put his three wins in a larger context, said they had expected such a result.
Mo Elleithee, a Clinton campaign spokesperson, told Time magazine that "Senator Obama's got a lot of built-in advantages across the region. Having said that, we will be able to do well enough to win our fair share of delegates."
Clinton campaigned Tuesday night in Texas, addressing supporters even as the media projected her losses in the Potomac primaries. She has made the Texas and Ohio contests on March 4 the centerpiece of her campaigning.
"Texas needs a president that actually understands what it takes to turn the economy around, get us universal health care, save hardworking American homes from foreclosure and abusive practices of mortgage companies," Clinton told a rally in El Paso.
Clinton has seen a windfall of financial support since Super Tuesday, but has trailed Obama's fundraising successes. Her faltering campaign got a shake-up this week, with the campaign manager and the deputy campaign manager leaving.
Clinton has begun running ads in Ohio and Texas and has renewed her call for more than two tentatively scheduled debates between her and Obama in the coming weeks.
But for the Clinton campaign, even its supporters have expressed the need to do well on March 4.
"She has to win both Ohio and Texas comfortably, or she's out," one anonymous super delegate who has endorsed Clinton told The New York Times. "The campaign is starting to come to terms with that."