Southfield, Mich. — As other Republican candidates have stumbled their way toward the presidential primaries, Mitt Romney has put together what would seem to be all the elements of a winning campaign: an effective staff, a robust treasury and smooth, knowledgeable performances both in debates and on the trail. But for months, the threshold of support for the former Massachusetts governor hasn't inched above a quarter of Republican voters in national polls. For many GOP voters in early primary states, hesitation about Romney comes back to one thing: their perception that he has routinely molded his views to suit the...