By Stephen Dinan

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**FILE** President Obama speaks Aug., 6, 2012, at a campaign fundraiser in ... more >

When Mitt Romney taps Rep. Paul Ryan to be his running mate on Saturday, he is picking someone who has already tangled toe-to-toe with President Obama on several occasions, and is prepared for the bruising battle ahead.
Indeed, Mr. Obama has built up plenty of bad blood with Mr. Ryan, calling him the architect of “social Darwinism” earlier this year, stemming from the Wisconsin Republican’s budget plan.