Republican presidential hopeful Mitt Romney wins the Michigan primary by a wide margin over John McCain. Mike Huckabee places third. Romney put a lot of money into last-minute ads in Michigan, persuading independent voters. The GOP presidential hopefuls head to South Carolina for its GOP primary on Saturday. Huckabee is expected to do well there among social conservatives and evangelicals. One of the key changes to the campaign is the candidates' focus on the economy. Previously, immigration and Iraq were the dominant issues.