As Barack Obama does better along the road to the Democratic nomination, he is sounding like a more confident candidate. That is to say he has begun to set his sights less on Hillary Clinton while focusing more on John McCain.

Today Obama told some 11,000 Marylanders at a Baltimore arena that he could handle the “Republican Attack Machine,” as dubbed by Clinton. “I have to explain to people, I’m skinny, but I’m tough,” he said to thunderous applause and laughter. “I’m wiry. Don’t mess with me! Let ‘em bring it on,” he said, growing more self assured as the crowd encouraged him. “Who they got? John McCain?”

The crowd was hooting at this point, but Obama quickly qualified himself. “Listen, listen - I respect John McCain for his half century of service to this country. He is, he is a genuine war hero and we need to honor him for that. He has gone through things most of us cannot imagine. He deserves applause. He deserves our respect,” he said, politely acknowledging McCain’s service.

And then he unloaded. “But, he is on the wrong side of history right now. He wants to perpetuate the Bush economic agenda that has failed working Americans. We don’t need more of that. He wants to perpetuate Bush’s foreign policy, talking about a hundred-year war in Iraq. We don’t need more of that. I am happy to have a debate with John McCain because we are the party of tomorrow; he is the party of yesterday. He’s the past; we’re the future. That’s an argument I want to have with the Republican Party,” he said forcefully.

The Obama equation is a complicated one. On one hand, he must convince Democrats he is tough enough to take on the Republicans, while at the same time, not disenfranchising the Republicans (or “Obamacans,” as he calls them) and Independents he seeks to win over.

So after Obama declared his intent to have an argument with the Republican Party, he ended on a sweet note. “Not to mention, I want to attract some Republicans into the fold,” he said. “We’re gonna build a coalition, a working majority to provide health care for everybody, and schools for kids, and college scholarships. That’s how you win an election. Not by turning people off, but by bringing ‘em in. Not by being angry all the time, but by being hopeful.”

But for now, at least, it still seems to be a delicate balancing act for the candidate.