SAN JUAN, P.R. — The pickup truck that carried him through Iowa is long gone, replaced by a small motorcade of S.U.V.’s. There was a police escort, and a phalanx of Secret Service agents. The sweater vest was gone, at least for the day, and Rick Santorum, the winner of the last two presidential primaries, was smartly turned out, in a dark suit and power tie, when he held a half-hour private meeting with Gov. Luis G. Fortuño of Puerto Rico.The two men did not take questions from reporters, but allowed photographers to capture the moment. With the cameras whirring,...