MAKING THE CASE FOR A MCCAIN MATCH-UP….Now that Democrats feel confident about which Republican they’re going to face in November, the race for the Democratic nomination appears poised to enter a slightly different phase: Barack Obama and Hillary Clinton will start making the case that they can beat John McCain in a general election, and their rival can’t.

To be sure, electability has been a part of the campaign process from the beginning, but it was always more of a broad, general pitch about the candidates’ appeal. Now, it’s going to get focused — Dems aren’t just talking about taking on a generic Republican opponent anymore; they’re talking about a specific, known quantity.

For his part, Obama seized on a perceived opportunity at an event at the University of Denver yesterday.

“It’s time for new leadership that understands that the way to win a debate with John McCain is not by nominating someone who agreed with him on voting for the war in Iraq,” Mr. Obama said, “who agreed with him in voting to give George Bush the benefit of the doubt on Iran; who agrees with him in embracing the Bush-Cheney policy of not talking to leaders we don’t like.”

He added, “We need to offer the American people a clear contrast on national security, and when I am the nominee of the Democratic Party, that’s exactly what I will do. Talking tough and tallying up your years in Washington is no substitute for judgment, and courage, and clear plans. It’s not enough to say you’ll be ready from Day One — you have to be right from Day One.”

As it stands, I actually think this is a healthy development. Clinton and Obama agree on most policy issues, and it gets tiresome to hear them argue about peripheral points. Having a GOP rival in mind should help focus the debate between them, with each able to make the case for how and why they can win the election.

As far as I can tell, the basic pitch from Obama’s perspective will be: He appeals to more independents and frustrated Republicans than Clinton; he represents a better contrast (old vs. young, new vs. stale); and he unites the left and divides the right, while Clinton divides the left and unites the right.

And the basic pitch from Clinton’s perspective will be: She has better support among independents and frustrated Republicans than the conventional wisdom suggests; McCain will make Obama look young and inexperienced — especially on matters regarding the military and national security — a line he can’t use against her; and the right may rally against her, but she knows how to deal with their attacks, persevere, and come out ahead. Can we say the same about Obama?

We’ll probably see quite a bit of this at tonight’s debate on CNN, the first head-to-head debate of the year. Should be interesting.

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Follow Steve on Twitter @stevebenen. Steve Benen is a producer at MSNBC's The Rachel Maddow Show. He was the principal contributor to the Washington Monthly's Political Animal blog from August 2008 until January 2012.