After John East, a stalwart conservative from North Carolina, entered the U.S. Senate in 1981, wags began referring to Jesse Helms as "the liberal senator from the Tar Heel state." We are reminded of this tale as Republican activists rush to encourage, if not yet fully embrace, the presidential candidacy of Fred Thompson, the former senator from Tennessee. The Republican base is evidently unimpressed or uninspired (or both) by the conservative credentials of the top three Republicans (John McCain, Mitt Romney and Rudy Giuliani) seeking the 2008 presidential nomination. Mr. Thompson's most-oft-cited conservative credential is his 86.1 percent lifetime (1995-2002)...