Even before Ben Carson shot to the lead of the Republican presidential race in Iowa, rival campaigns from Donald Trump down began grappling with the question: How to defeat the genial, soft-spoken, African-American brain surgeon who has quietly captured the imagination of so many GOP voters?

The answer: very carefully. “I don’t think we run against Carson,” said a strategist for a GOP campaign over the weekend. “He’s just so well-liked that it is tough.” The problem, of course, is that if Carson remains atop the polls in Iowa, and sits in a solid second place in the national polls, other candidates will likely feel compelled to go after him.