The political landscape may be shifting in ways that would make it easier for Sen. John McCain of Arizona to win the 2008 Republican presidential nomination. He's among several potential candidates courting Southern and Midwest Republicans this weekend in Memphis, Tenn., in the first chance that party insiders have had to look at several would-be nominees in one place. Conventional wisdom — that McCain could win the general election but not the Republican nomination because conservatives oppose him — may be changing. A convergence of three new forces could be reshaping the landscape just as Republicans begin deciding who will...