WASHINGTON - As Republicans look to the 2008 primaries in search of a candidate whose credentials and personality can triumph over Senator Clinton, one potential candidate has no expectation of winning on the basis of his personality or record - or of winning at all, for that matter. Instead, Rep. Thomas Tancredo, a Republican of Colorado, is hoping that his participation in Iowa's caucuses and early primaries will bring a victory for his signature issue: immigration reform. He isn't waiting until 2008. Mr. Tancredo, 59, who has earned a national reputation for being an advocate for stricter border controls on...