Here's the fail-safe test for whether a political party is growing and strengthening or shrinking in size and prospects: Is that party spending its time, energy and effort seeking, recruiting and welcoming converts to its ranks, or is that party instead hunting down heretics within its ranks and, in the name of political purity, banishing them to some outer darkness?
Because American politics is always a matter of addition, not subtraction, the convert-seeking and convert-welcoming party is healthier and almost always has the better prospects of winning the November general election. Republicans understood that well in 1980 when the GOP presidential nominee openly courted and embraced converts, even giving them very own designation as Reagan Democrats. At the 2004 Democratic National Convention, the future Democratic nominee told the nation: "There is not a liberal America and a conservative America. There is the United States of America." Thus did Barack Obama become the first Democrat in 12 presidential elections to win 53 percent of the national Vote.