Less than 24 hours after sweeping three state primaries to become the Republicans' de facto presidential nominee, Mitt Romney on Wednesday took the same stage where his ultimate rival, Barack Obama, had already spoken. The dueling speeches, on successive days, provided a glimpse of the general-election campaign now underway.

Now is not the time for President Obama's hide-and-seek campaign, Romney told a Washington conference of newspaper editors and executives in a rebuttal to Obama's remarks to the same audience a day earlier.

Romney has been attacking Obama since the beginning of the Repubican primary season, but the president on Tuesday broke from routine by mentioning the ex-Massachusetts governor by name. Obama blasted the budget plan proposed by Republican congressman and Romney backer Paul Ryan as a far-right assault on low-income and middle-class Americans.

One of my potential opponents, Governor Romney, has said that he hoped a similar version of this plan from last year would be introduced as a bill on day one of his presidency, Obama said. He said that he's very supportive of this new budget. And he even called it 'marvelous,' which is a word you don't often hear when it comes to describing a budget. It's a word you don't often hear generally.

The reference is a sign that Obama has focused his line of attack to the challenger he expects to face in November. That's hardly a surprise given that Romney's primary wins Tuesday in Wisconsin, Maryland and the District of Columbia push him closer to his party's nomination and make it harder for Rick Santorum to stay in the race.

Exit polls showed that Romney finally won over the Tea Party movement and very conservative voters, a bloc he has continually lost to Santorum and Newt Gingrich. Romney was chosen by 51 percent of Wisconsin primary voters who said they strongly support the movement, and 48 percent of those in Maryland. Eight in 10 voters also said they believe he will be the nominee.

Santorum was desperately clinging to his candidacy Tuesday night in his home state of Pennsylvania before his latest primary losses were reported. It's halftime, he said. We forged liberty in this state, Santorum said, comparing himself to George Washington crossing the Delaware River during the Revolutionary War. Pennsylvania and four other states conduct primaries on April 24.

It's now virtually impossible for Santorum to catch up in the all-important hunt for nomination delegates. Romney took in 86 of 95 delegates on Tuesday and has won 58 percent of the primary and caucus delegates so far, the Associated Press calculates.

And the Pennsylvania victory Santorum is banking on won't be easy. Romney sent full-time campaign staffers to the state last week and the super PAC that supports him has already made inquiries about buying local television ads, the Hill newspaper reported.

Democratic strategist James Carville, known for colorful comments, described what he considers the harsh reality for Republicans. Santorum, he told CNN, is like a chicken with his head chopped off. The chicken is dead. The only person that don't know it is the chicken.