As influential as they are, Limbaugh, Coulter and Erickson don’t set the agenda for Republicans. But their reactions underscore the continued fragility of Romney’s relationship with the conservative world. When Romney hews to a strongly conservative line, he is fine. But when the former Massachusetts governor sends any signal — a poorly worded phrase, a staffer’s mistake — that sounds like something a conservative would not say, some of his critics on the right immediately recoil and say, “See — I knew he wasn’t one of us.”

Romney has grappled with the problem from the moment he entered national politics. This year, it accounted for one of the more awkward moments of the campaign, his February speech to the Conservative Political Action Conference in which he used the word “conservative” more than 20 times and noted that he was “a severely conservative Republican governor” in Massachusetts.

Many Republicans hoped the problem would go away in the general election campaign. After all, in the primaries Romney was trying to convince mostly conservative Republicans that he was a better candidate than his mostly conservative rivals. Now, as Romney runs against President Obama, many supporters hoped Romney would face fewer calls to prove his conservative bona fides.