At various times during the past few months, as many as 25 percent of Democrats have said they’ll vote for John McCain if Barack Obama/Hillary Rodham Clinton is not the party nominee. Some conservative Republicans have said stormily they’ll vote for the Democrat over McCain because they think he’s too liberal. After the sturm und drang of the Democratic primary season (and it will end), what can we expect for the fall election? We will see both parties running full-tilt to win the White House. The issues are simply too critical for mainstream Democrats and mainstream Republicans to 1) throw...