Democrats have rediscovered federalism not long after they rediscovered a love of the plain text of the Constitution when the GOP threatened to alter it to deal with marriage. Terri Schiavo is the issue now.
What the Democrats don’t understand is that federalism is scarcely in the DNA of the Republican party. The GOP fought against slavery and polygamy in the 19th century heedless of states’ rights in the process. The key issue for the GOP has traditionally been the dignity of the individual in a moral universe. Slavery and polygamy offended that principle because they involved lopsided relationships. The GOP fought the New Deal and socialism for the same reason. Statism tended to rob the individual of God-given dignity and introduce a new lopsided relationship – the individual before a monolith state.
The modern GOP has embraced federalism, but primarily as a method of keeping solutions as close to the individual as possible. States’ rights are a means, not an end in the GOP philosophy. It is the Democrats who made states’ rights the end-all-be-all during the era of slavery and later Jim Crow.