The Pew survey that dissects both Democrats and Republicans into separate groups and polls them on different issues is a fascinating insight into our current politics. It divides Republicans into three groups: "Enterprisers", "Social Conservatives" and "Pro-Government Conservatives." (On that map, I'd be an "enterpriser.") On several issues - the role of government, the power of big business, government regulation, the environment, government's moralizing role - enterprisers are alone, and in opposition to "social cons" and "pro-gov cons." But on immigration, the enterprisers and pro-gov cons agree with the proposition that "the growing number of newcomers from other countries strengthens American society." Enterprisers back this by a margin of 53 to 38 percent; pro-gov cons back it by an even bigger margin of 62 to 31 percent. But social conservatives believe that growing immigration "threatens traditional American customs and values" by a margin of 68 to 21 percent. If you think of the Bush-Rove years as an attempt to build up the pro-government and social conservatives against the enterprisers, then immigration is a big problem for them. It unravels the Rove coalition. The more heated the debate, the more the Republicans divide. The Democrats are divided too. But because they aren't in power, the effect is more muted.(Photo: Dave Einsel/Getty Images)